blocks|key|114758|text|您可能想看看我的自由/开源软件项目CSVfix+()，它是一个用C%2B%2B编写的CSV流编辑器。CSV解析器不是什么好东西，但它可以完成这项工作，并且整个包都可以完成您所需的工作，而无需编写任何代码。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|114759|有关CSV解析器的信息，请参阅alib/src/a_csv.cpp；有关使用示例，请参阅csvlib/src/csved_ioman.cpp+(IOManager::ReadCSV)。|style|CODE|114760|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/p/csvfix/|1|https://bitbucket.org/neilb/csvfix/src/default/alib/src/a_csv.cpp?fileviewer=file-view-default|2|https://bitbucket.org/neilb/csvfix/src/default/csvfix/src/csved_ioman.cpp?fileviewer=file-view-default#csved_ioman.cpp-348^0|H|6|0|0|20|I|F|I|1|18|Q|2|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@$A|U|B|V|1|W]]|C|$]]|$1|D|3|E|5|6|7|X|8|@$A|Y|B|Z|F|G]]|9|@$A|10|B|11|1|12]|$A|13|B|14|1|15]]|C|$]]|$1|H|3|-4|5|6|7|16|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]|P|$5|K|L|M|C|$N|Q]]|R|$5|K|L|M|C|$N|S]]]]

You might want to look at my FOSS project <a href="http://code.google.com/p/csvfix/" rel="nofollow noreferrer">CSVfix</a> (<a href="https://bitbucket.org/neilb/csvfix/" rel="nofollow noreferrer">updated link</a>), which is a CSV stream editor written in C++. The CSV parser is no prize, but does the job and the whole package may do what you need without you writing any code.

See <a href="https://bitbucket.org/neilb/csvfix/src/default/alib/src/a_csv.cpp?fileviewer=file-view-default" rel="nofollow noreferrer">alib/src/a_csv.cpp</a> for the CSV parser, and <a href="https://bitbucket.org/neilb/csvfix/src/default/csvfix/src/csved_ioman.cpp?fileviewer=file-view-default#csved_ioman.cpp-348" rel="nofollow noreferrer">csvlib/src/csved_ioman.cpp</a> (<code>IOManager::ReadCSV</code>) for a usage example.

blocks|key|114790|text|如果您不关心转义逗号和换行符，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|114791|并且不能在引号中嵌入逗号和换行符(如果无法转义，则...)|114792|然后它只有三行代码(OK+14+->But读取整个文件只有15行)。|114793|std::vector<std::string>+getNextLineAndSplitIntoTokens(std::istream&+str)
{
++++std::vector<std::string>+++result;
++++std::string++++++++++++++++line;
++++std::getline(str,line);

++++std::stringstream++++++++++lineStream(line);
++++std::string++++++++++++++++cell;

++++while(std::getline(lineStream,cell,+','))
++++{
++++++++result.push_back(cell);
++++}
++++//+This+checks+for+a+trailing+comma+with+no+data+after+it.
++++if+(!lineStream+&&+cell.empty())
++++{
++++++++//+If+there+was+a+trailing+comma+then+add+an+empty+element.
++++++++result.push_back("");
++++}
++++return+result;
}|code-block|syntax|javascript|114794|我只需要创建一个表示行的类。|114795|然后流到该对象：|114796|#include+<iterator>
#include+<iostream>
#include+<fstream>
#include+<sstream>
#include+<vector>
#include+<string>

class+CSVRow
{
++++public:
++++++++std::string_view+operator[](std::size_t+index)+const
++++++++{
++++++++++++return+std::string_view(&m_line[m_data[index]+%2B+1],+m_data[index+%2B+1]+-++(m_data[index]+%2B+1));
++++++++}
++++++++std::size_t+size()+const
++++++++{
++++++++++++return+m_data.size()+-+1;
++++++++}
++++++++void+readNextRow(std::istream&+str)
++++++++{
++++++++++++std::getline(str,+m_line);

++++++++++++m_data.clear();
++++++++++++m_data.emplace_back(-1);
++++++++++++std::string::size_type+pos+=+0;
++++++++++++while((pos+=+m_line.find(',',+pos))+!=+std::string::npos)
++++++++++++{
++++++++++++++++m_data.emplace_back(pos);
++++++++++++++++%2B%2Bpos;
++++++++++++}
++++++++++++//+This+checks+for+a+trailing+comma+with+no+data+after+it.
++++++++++++pos+++=+m_line.size();
++++++++++++m_data.emplace_back(pos);
++++++++}
++++private:
++++++++std::string+++++++++m_line;
++++++++std::vector<int>++++m_data;
};

std::istream&+operator>>(std::istream&+str,+CSVRow&+data)
{
++++data.readNextRow(str);
++++return+str;
}+++
int+main()
{
++++std::ifstream+++++++file("plop.csv");

++++CSVRow++++++++++++++row;
++++while(file+>>+row)
++++{
++++++++std::cout+<<+"4th+Element("+<<+row[3]+<<+")\n";
++++}
}|114797|但只需做一点工作，我们就可以从技术上创建一个迭代器：|114798|class+CSVIterator
{+++
++++public:
++++++++typedef+std::input_iterator_tag+++++iterator_category;
++++++++typedef+CSVRow++++++++++++++++++++++value_type;
++++++++typedef+std::size_t+++++++++++++++++difference_type;
++++++++typedef+CSVRow*+++++++++++++++++++++pointer;
++++++++typedef+CSVRow&+++++++++++++++++++++reference;

++++++++CSVIterator(std::istream&+str)++:m_str(str.good()?&str:NULL)+{+%2B%2B(*this);+}
++++++++CSVIterator()+++++++++++++++++++:m_str(NULL)+{}

++++++++//+Pre+Increment
++++++++CSVIterator&+operator%2B%2B()+++++++++++++++{if+(m_str)+{+if+(!((*m_str)+>>+m_row)){m_str+=+NULL;}}return+*this;}
++++++++//+Post+increment
++++++++CSVIterator+operator%2B%2B(int)+++++++++++++{CSVIterator++++tmp(*this);%2B%2B(*this);return+tmp;}
++++++++CSVRow+const&+operator*()+++const+++++++{return+m_row;}
++++++++CSVRow+const*+operator->()++const+++++++{return+&m_row;}

++++++++bool+operator==(CSVIterator+const&+rhs)+{return+((this+==+&rhs)+%7C%7C+((this->m_str+==+NULL)+&&+(rhs.m_str+==+NULL)));}
++++++++bool+operator!=(CSVIterator+const&+rhs)+{return+!((*this)+==+rhs);}
++++private:
++++++++std::istream*+++++++m_str;
++++++++CSVRow++++++++++++++m_row;
};


int+main()
{
++++std::ifstream+++++++file("plop.csv");

++++for(CSVIterator+loop(file);+loop+!=+CSVIterator();+%2B%2Bloop)
++++{
++++++++std::cout+<<+"4th+Element("+<<+(*loop)[3]+<<+")\n";
++++}
}|114799|现在我们已经进入2020年了，让我们添加一个CSVRange对象：|114800|class+CSVRange
{
++++std::istream&+++stream;
++++public:
++++++++CSVRange(std::istream&+str)
++++++++++++:+stream(str)
++++++++{}
++++++++CSVIterator+begin()+const+{return+CSVIterator{stream};}
++++++++CSVIterator+end()+++const+{return+CSVIterator{};}
};

int+main()
{
++++std::ifstream+++++++file("plop.csv");

++++for(auto&+row:+CSVRange(file))
++++{
++++++++std::cout+<<+"4th+Element("+<<+row[3]+<<+")\n";
++++}
}|114801|entityMap^0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|12|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|13|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|14|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|A|$]]|$1|O|3|P|5|H|7|16|8|@]|9|@]|A|$I|J]]|$1|Q|3|R|5|6|7|17|8|@]|9|@]|A|$]]|$1|S|3|T|5|H|7|18|8|@]|9|@]|A|$I|J]]|$1|U|3|V|5|6|7|19|8|@]|9|@]|A|$]]|$1|W|3|X|5|H|7|1A|8|@]|9|@]|A|$I|J]]|$1|Y|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|Z|$]]

If you don't care about escaping comma and newline, 
AND you can't embed comma and newline in quotes (If you can't escape then...) 
then its only about three lines of code (OK 14 -&gt;But its only 15 to read the whole file).
<pre><code>std::vector&lt;std::string&gt; getNextLineAndSplitIntoTokens(std::istream&amp; str)
{
 std::vector&lt;std::string&gt; result;
 std::string line;
 std::getline(str,line);

 std::stringstream lineStream(line);
 std::string cell;

 while(std::getline(lineStream,cell, ','))
 {
 result.push_back(cell);
 }
 // This checks for a trailing comma with no data after it.
 if (!lineStream &amp;&amp; cell.empty())
 {
 // If there was a trailing comma then add an empty element.
 result.push_back(&quot;&quot;);
 }
 return result;
}
</code></pre>
I would just create a class representing a row. 
Then stream into that object:
<pre><code>#include &lt;iterator&gt;
#include &lt;iostream&gt;
#include &lt;fstream&gt;
#include &lt;sstream&gt;
#include &lt;vector&gt;
#include &lt;string&gt;

class CSVRow
{
 public:
 std::string_view operator[](std::size_t index) const
 {
 return std::string_view(&amp;m_line[m_data[index] + 1], m_data[index + 1] - (m_data[index] + 1));
 }
 std::size_t size() const
 {
 return m_data.size() - 1;
 }
 void readNextRow(std::istream&amp; str)
 {
 std::getline(str, m_line);

 m_data.clear();
 m_data.emplace_back(-1);
 std::string::size_type pos = 0;
 while((pos = m_line.find(',', pos)) != std::string::npos)
 {
 m_data.emplace_back(pos);
 ++pos;
 }
 // This checks for a trailing comma with no data after it.
 pos = m_line.size();
 m_data.emplace_back(pos);
 }
 private:
 std::string m_line;
 std::vector&lt;int&gt; m_data;
};

std::istream&amp; operator&gt;&gt;(std::istream&amp; str, CSVRow&amp; data)
{
 data.readNextRow(str);
 return str;
} 
int main()
{
 std::ifstream file(&quot;plop.csv&quot;);

 CSVRow row;
 while(file &gt;&gt; row)
 {
 std::cout &lt;&lt; &quot;4th Element(&quot; &lt;&lt; row[3] &lt;&lt; &quot;)\n&quot;;
 }
}
</code></pre>
But with a little work we could technically create an iterator:
<pre><code>class CSVIterator
{ 
 public:
 typedef std::input_iterator_tag iterator_category;
 typedef CSVRow value_type;
 typedef std::size_t difference_type;
 typedef CSVRow* pointer;
 typedef CSVRow&amp; reference;

 CSVIterator(std::istream&amp; str) :m_str(str.good()?&amp;str:NULL) { ++(*this); }
 CSVIterator() :m_str(NULL) {}

 // Pre Increment
 CSVIterator&amp; operator++() {if (m_str) { if (!((*m_str) &gt;&gt; m_row)){m_str = NULL;}}return *this;}
 // Post increment
 CSVIterator operator++(int) {CSVIterator tmp(*this);++(*this);return tmp;}
 CSVRow const&amp; operator*() const {return m_row;}
 CSVRow const* operator-&gt;() const {return &amp;m_row;}

 bool operator==(CSVIterator const&amp; rhs) {return ((this == &amp;rhs) || ((this-&gt;m_str == NULL) &amp;&amp; (rhs.m_str == NULL)));}
 bool operator!=(CSVIterator const&amp; rhs) {return !((*this) == rhs);}
 private:
 std::istream* m_str;
 CSVRow m_row;
};


int main()
{
 std::ifstream file(&quot;plop.csv&quot;);

 for(CSVIterator loop(file); loop != CSVIterator(); ++loop)
 {
 std::cout &lt;&lt; &quot;4th Element(&quot; &lt;&lt; (*loop)[3] &lt;&lt; &quot;)\n&quot;;
 }
}
</code></pre>
Now that we are in 2020 lets add a CSVRange object:
<pre><code>class CSVRange
{
 std::istream&amp; stream;
 public:
 CSVRange(std::istream&amp; str)
 : stream(str)
 {}
 CSVIterator begin() const {return CSVIterator{stream};}
 CSVIterator end() const {return CSVIterator{};}
};

int main()
{
 std::ifstream file(&quot;plop.csv&quot;);

 for(auto&amp; row: CSVRange(file))
 {
 std::cout &lt;&lt; &quot;4th Element(&quot; &lt;&lt; row[3] &lt;&lt; &quot;)\n&quot;;
 }
}
</code></pre>

blocks|key|115719|text|使用Boost+Tokenizer的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|115720|std::vector<std::string>+vec;
using+namespace+boost;
tokenizer<escaped_list_separator<char>+>+tk(
+++line,+escaped_list_separator<char>('\\',+',',+'\"'));
for+(tokenizer<escaped_list_separator<char>+>::iterator+i(tk.begin());
+++i!=tk.end();%2B%2Bi)+
{
+++vec.push_back(*i);
}|code-block|syntax|javascript|115721|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Solution using Boost Tokenizer:

<pre><code>std::vector&lt;std::string&gt; vec;
using namespace boost;
tokenizer&lt;escaped_list_separator&lt;char&gt; &gt; tk(
 line, escaped_list_separator&lt;char&gt;('\\', ',', '\"'));
for (tokenizer&lt;escaped_list_separator&lt;char&gt; &gt;::iterator i(tk.begin());
 i!=tk.end();++i) 
{
 vec.push_back(*i);
}
</code></pre>

blocks|key|1417078|text|对不起，这一切看起来像是隐藏了几行代码的大量精心设计的语法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1417079|为什么不这样：|1417080|/**

++Read+line+from+a+CSV+file

++@param[in]+fp+file+pointer+to+open+file
++@param[in]+vls+reference+to+vector+of+strings+to+hold+next+line

++*/
void+readCSV(+FILE+*fp,+std::vector<std::string>&+vls+)
{
++++vls.clear();
++++if(+!+fp+)
++++++++return;
++++char+buf[10000];
++++if(+!+fgets(+buf,999,fp)+)
++++++++return;
++++std::string+s+=+buf;
++++int+p,q;
++++q+=+-1;
++++//+loop+over+columns
++++while(+1+)+{
++++++++p+=+q;
++++++++q+=+s.find_first_of(",\n",p%2B1);
++++++++if(+q+==+-1+)+
++++++++++++break;
++++++++vls.push_back(+s.substr(p%2B1,q-p-1)+);
++++}
}

int+_tmain(int+argc,+_TCHAR*+argv[])
{
++++std::vector<std::string>+vls;
++++FILE+*+fp+=+fopen(+argv[1],+"r"+);
++++if(+!+fp+)
++++++++return+1;
++++readCSV(+fp,+vls+);
++++readCSV(+fp,+vls+);
++++readCSV(+fp,+vls+);
++++std::cout+<<+"row+3,+col+4+is+"+<<+vls[3].c_str()+<<+"\n";

++++return+0;
}|code-block|syntax|javascript|1417081|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Excuse me, but this all seems like a great deal of elaborate syntax to hide a few lines of code.

Why not this:

<pre><code>/**

 Read line from a CSV file

 @param[in] fp file pointer to open file
 @param[in] vls reference to vector of strings to hold next line

 */
void readCSV( FILE *fp, std::vector&lt;std::string&gt;&amp; vls )
{
 vls.clear();
 if( ! fp )
 return;
 char buf[10000];
 if( ! fgets( buf,999,fp) )
 return;
 std::string s = buf;
 int p,q;
 q = -1;
 // loop over columns
 while( 1 ) {
 p = q;
 q = s.find_first_of(",\n",p+1);
 if( q == -1 ) 
 break;
 vls.push_back( s.substr(p+1,q-p-1) );
 }
}

int _tmain(int argc, _TCHAR* argv[])
{
 std::vector&lt;std::string&gt; vls;
 FILE * fp = fopen( argv[1], "r" );
 if( ! fp )
 return 1;
 readCSV( fp, vls );
 readCSV( fp, vls );
 readCSV( fp, vls );
 std::cout &lt;&lt; "row 3, col 4 is " &lt;&lt; vls[3].c_str() &lt;&lt; "\n";

 return 0;
}
</code></pre>

blocks|key|1417105|text|您还可以了解一下Qt库的功能。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1417106|它支持正则表达式，QString类有很好的方法，例如split()返回QStringList，通过使用提供的分隔符拆分原始字符串而获得的字符串列表。对于csv文件应该足够了..|1417107|要获取具有给定标题名称的列，我使用以下命令：c%2B%2B+inheritance+Qt+problem+qstring|1417108|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/970330/c-inheritance-qt-problem-qstring/1011601#1011601^0|8|2|0|Q|7|0|M|Y|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|X|8|@]|D|@$9|Y|A|Z|1|10]]|E|$]]|$1|J|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

You could also take a look at capabilities of <code>Qt</code> library.

It has regular expressions support and QString class has nice methods, e.g. <code>split()</code> returning QStringList, list of strings obtained by splitting the original string with a provided delimiter. Should suffice for csv file.. 

To get a column with a given header name I use following: <a href="https://stackoverflow.com/questions/970330/c-inheritance-qt-problem-qstring/1011601#1011601">c++ inheritance Qt problem qstring</a>

blocks|key|1417117|text|将Boost+Tokenizer+escaped_list_separator用于CSV文件时，应注意以下事项：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1417118|1417119|它需要转义字符(默认反斜杠-)|ordered-list-item|1417120|它需要分隔符/分隔符(默认逗号-，)|1417121|它需要引号字符(默认引号-+")|1417122|1417123|wiki指定的CSV格式规定数据字段可以在引号中包含分隔符(支持)：|1417124|1417125|+1997，福特，E350，“超级豪华卡车”|blockquote|1417126|1417127|1417128|wiki指定的CSV格式规定应使用双引号处理单引号(escaped_list_separator将去掉所有引号字符)：|1417129|1417130|+1997，福特，E350，“超级”，“豪华”，“卡车”|1417131|1417132|1417133|CSV格式没有指定应该去掉任何反斜杠字符(escaped_list_separator将去掉所有转义字符)。|1417134|修复boost+escaped_list_separator默认行为的可能解决方法：|1417135|1417136|首先将所有反斜杠字符()替换为两个反斜杠字符(\)，这样它们就不会被剥离，并将所有双引号("")替换为单反斜杠字符和引号(\")|1417137|1417138|这种变通方法的副作用是，由双引号表示的空数据字段将转换为单引号标记。在迭代标记时，必须检查标记是否为单引号，并将其视为空字符串。|1417139|不是很漂亮，但只要引号中没有换行符，它就可以工作。|1417140|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|1F|8|@]|9|@]|A|$]]|$1|F|3|G|5|E|7|1G|8|@]|9|@]|A|$]]|$1|H|3|I|5|E|7|1H|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|1J|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|1K|8|@]|9|@]|A|$]]|$1|N|3|O|5|P|7|1L|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|1M|8|@]|9|@]|A|$]]|$1|R|3|-4|5|6|7|1N|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1O|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]|$1|V|3|W|5|P|7|1Q|8|@]|9|@]|A|$]]|$1|X|3|-4|5|6|7|1R|8|@]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|1S|8|@]|9|@]|A|$]]|$1|Z|3|10|5|6|7|1T|8|@]|9|@]|A|$]]|$1|11|3|12|5|6|7|1U|8|@]|9|@]|A|$]]|$1|13|3|-4|5|6|7|1V|8|@]|9|@]|A|$]]|$1|14|3|15|5|E|7|1W|8|@]|9|@]|A|$]]|$1|16|3|-4|5|6|7|1X|8|@]|9|@]|A|$]]|$1|17|3|18|5|6|7|1Y|8|@]|9|@]|A|$]]|$1|19|3|1A|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|1B|3|-4|5|6|7|20|8|@]|9|@]|A|$]]]|1C|$]]

When using the Boost Tokenizer escaped_list_separator for CSV files, then one should be aware of the following:

<ol>
<li>It requires an escape-character (default back-slash - \)</li>
<li>It requires a splitter/seperator-character (default comma - ,)</li>
<li>It requires an quote-character (default quote - ")</li>
</ol>

The CSV format specified by wiki states that data fields can contain separators in quotes (supported):

<blockquote>
 1997,Ford,E350,"Super, luxurious truck"
</blockquote>

The CSV format specified by wiki states that single quotes should be handled with double-quotes (escaped_list_separator will strip away all quote characters):

<blockquote>
 1997,Ford,E350,"Super ""luxurious"" truck"
</blockquote>

The CSV format doesn't specify that any back-slash characters should be stripped away (escaped_list_separator will strip away all escape characters).

A possible work-around to fix the default behavior of the boost escaped_list_separator:

<ol>
<li>First replace all back-slash characters (\) with two back-slash characters (\\) so they are not stripped away.</li>
<li>Secondly replace all double-quotes ("") with a single back-slash character and a quote (\")</li>
</ol>

This work-around has the side-effect that empty data-fields that are represented by a double-quote, will be transformed into a single-quote-token. When iterating through the tokens, then one must check if the token is a single-quote, and treat it like an empty string.

Not pretty but it works, as long there are not newlines within the quotes.

blocks|key|114906|text|使用Spirit解析CSV并不过分。Spirit非常适合于微解析任务。例如，使用Spirit+2.1，它就像这样简单：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|114907|bool+r+=+phrase_parse(first,+last,

++++//++Begin+grammar
++++(
++++++++double_+%25+','
++++)
++++,
++++//++End+grammar

++++space,+v);|code-block|syntax|javascript|114908|向量v被值填充。There+is+a+series+of+tutorials在新的Spirit+2.1文档中涉及到这一点，该文档刚刚与Boost+1.41一起发布。|offset|length|114909|本教程从简单到复杂。CSV解析器位于中间的某个位置，涉及使用Spirit的各种技术。生成的代码与手写代码一样紧凑。检查生成的汇编程序！|114910|entityMap|0|LINK|mutability|MUTABLE|url|http://www.boost.org/doc/libs/1_41_0/libs/spirit/doc/html/spirit/qi/tutorials.html^0|0|0|8|U|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@$I|X|J|Y|1|Z]]|A|$]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

It is not overkill to use Spirit for parsing CSVs. Spirit is well suited for micro-parsing tasks. For instance, with Spirit 2.1, it is as easy as:

<pre><code>bool r = phrase_parse(first, last,

 // Begin grammar
 (
 double_ % ','
 )
 ,
 // End grammar

 space, v);
</code></pre>

The vector, v, gets stuffed with the values. <a href="http://www.boost.org/doc/libs/1_41_0/libs/spirit/doc/html/spirit/qi/tutorials.html" rel="noreferrer">There is a series of tutorials</a> touching on this in the new Spirit 2.1 docs that's just been released with Boost 1.41.

The tutorial progresses from simple to complex. The CSV parsers are presented somewhere in the middle and touches on various techniques in using Spirit. The generated code is as tight as hand written code. Check out the assembler generated!

blocks|key|4321476|text|您可以在escaped_list_separator中使用Boost+Tokenizer。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|4321477|csv+escaped_list_separator解析|4321478|的超集。Boost::tokenizer|blockquote|4321479|4321480|4321481|这只使用Boost标记器头文件，不需要链接到boost库。|4321482|下面是一个示例(有关详细信息或Boost::tokenizer，请参阅Parse+CSV+File+With+Boost+Tokenizer+In+C%2B%2B+)：|CODE|4321483|#include+<iostream>+++++//+cout,+endl
#include+<fstream>++++++//+fstream
#include+<vector>
#include+<string>
#include+<algorithm>++++//+copy
#include+<iterator>+++++//+ostream_operator
#include+<boost/tokenizer.hpp>

int+main()
{
++++using+namespace+std;
++++using+namespace+boost;
++++string+data("data.csv");

++++ifstream+in(data.c_str());
++++if+(!in.is_open())+return+1;

++++typedef+tokenizer<+escaped_list_separator<char>+>+Tokenizer;
++++vector<+string+>+vec;
++++string+line;

++++while+(getline(in,line))
++++{
++++++++Tokenizer+tok(line);
++++++++vec.assign(tok.begin(),tok.end());

++++++++//+vector+now+contains+strings+from+one+row,+output+to+cout+here
++++++++copy(vec.begin(),+vec.end(),+ostream_iterator<string>(cout,+"%7C"));

++++++++cout+<<+"\n----------------------"+<<+endl;
++++}
}|code-block|syntax|javascript|4321484|entityMap|0|LINK|mutability|MUTABLE|url|https://www.boost.org/doc/libs/release/libs/tokenizer/doc/escaped_list_separator.htm|1|http://mybyteofcode.blogspot.com/2010/02/parse-csv-file-with-boost-tokenizer-in.html^0|0|19|0|4|M|0|4|G|0|0|0|0|0|F|G|Z|16|1|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|19|8|@$9|1A|A|1B|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|1C|8|@]|D|@$9|1D|A|1E|1|1F]]|E|$]]|$1|K|3|-4|5|6|7|1G|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|1H|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|1I|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|1J|8|@$9|1K|A|1L|B|Q]]|D|@$9|1M|A|1N|1|1O]]|E|$]]|$1|R|3|S|5|T|7|1P|8|@]|D|@]|E|$U|V]]|$1|W|3|-4|5|6|7|1Q|8|@]|D|@]|E|$]]]|X|$Y|$5|Z|10|11|E|$12|13]]|14|$5|Z|10|11|E|$12|15]]]]

You can use Boost Tokenizer with escaped_list_separator.
<blockquote>
escaped_list_separator parses a superset of the csv. <a href="https://www.boost.org/doc/libs/release/libs/tokenizer/doc/escaped_list_separator.htm" rel="nofollow noreferrer">Boost::tokenizer</a>
</blockquote>
This only uses Boost tokenizer header files, no linking to boost libraries required.
Here is an example, (see <a href="http://mybyteofcode.blogspot.com/2010/02/parse-csv-file-with-boost-tokenizer-in.html" rel="nofollow noreferrer">Parse CSV File With Boost Tokenizer In C++</a> for details or <code>Boost::tokenizer</code> ):
<pre><code>#include &lt;iostream&gt; // cout, endl
#include &lt;fstream&gt; // fstream
#include &lt;vector&gt;
#include &lt;string&gt;
#include &lt;algorithm&gt; // copy
#include &lt;iterator&gt; // ostream_operator
#include &lt;boost/tokenizer.hpp&gt;

int main()
{
 using namespace std;
 using namespace boost;
 string data(&quot;data.csv&quot;);

 ifstream in(data.c_str());
 if (!in.is_open()) return 1;

 typedef tokenizer&lt; escaped_list_separator&lt;char&gt; &gt; Tokenizer;
 vector&lt; string &gt; vec;
 string line;

 while (getline(in,line))
 {
 Tokenizer tok(line);
 vec.assign(tok.begin(),tok.end());

 // vector now contains strings from one row, output to cout here
 copy(vec.begin(), vec.end(), ostream_iterator&lt;string&gt;(cout, &quot;|&quot;));

 cout &lt;&lt; &quot;\n----------------------&quot; &lt;&lt; endl;
 }
}
</code></pre>

blocks|key|114949|text|如果你关心如何正确解析CSV，这将会很慢，因为它一次只能处理一个字符。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|114950|+void+ParseCSV(const+string&+csvSource,+vector<vector<string>+>&+lines)
++++{
+++++++bool+inQuote(false);
+++++++bool+newLine(false);
+++++++string+field;
+++++++lines.clear();
+++++++vector<string>+line;

+++++++string::const_iterator+aChar+=+csvSource.begin();
+++++++while+(aChar+!=+csvSource.end())
+++++++{
++++++++++switch+(*aChar)
++++++++++{
++++++++++case+'"':
+++++++++++++newLine+=+false;
+++++++++++++inQuote+=+!inQuote;
+++++++++++++break;

++++++++++case+',':
+++++++++++++newLine+=+false;
+++++++++++++if+(inQuote+==+true)
+++++++++++++{
++++++++++++++++field+%2B=+*aChar;
+++++++++++++}
+++++++++++++else
+++++++++++++{
++++++++++++++++line.push_back(field);
++++++++++++++++field.clear();
+++++++++++++}
+++++++++++++break;

++++++++++case+'\n':
++++++++++case+'\r':
+++++++++++++if+(inQuote+==+true)
+++++++++++++{
++++++++++++++++field+%2B=+*aChar;
+++++++++++++}
+++++++++++++else
+++++++++++++{
++++++++++++++++if+(newLine+==+false)
++++++++++++++++{
+++++++++++++++++++line.push_back(field);
+++++++++++++++++++lines.push_back(line);
+++++++++++++++++++field.clear();
+++++++++++++++++++line.clear();
+++++++++++++++++++newLine+=+true;
++++++++++++++++}
+++++++++++++}
+++++++++++++break;

++++++++++default:
+++++++++++++newLine+=+false;
+++++++++++++field.push_back(*aChar);
+++++++++++++break;
++++++++++}

++++++++++aChar%2B%2B;
+++++++}

+++++++if+(field.size())
++++++++++line.push_back(field);

+++++++if+(line.size())
++++++++++lines.push_back(line);
++++}|code-block|syntax|javascript|114951|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you DO care about parsing CSV correctly, this will do it...relatively slowly as it works one char at a time.

<pre><code> void ParseCSV(const string&amp; csvSource, vector&lt;vector&lt;string&gt; &gt;&amp; lines)
 {
 bool inQuote(false);
 bool newLine(false);
 string field;
 lines.clear();
 vector&lt;string&gt; line;

 string::const_iterator aChar = csvSource.begin();
 while (aChar != csvSource.end())
 {
 switch (*aChar)
 {
 case '"':
 newLine = false;
 inQuote = !inQuote;
 break;

 case ',':
 newLine = false;
 if (inQuote == true)
 {
 field += *aChar;
 }
 else
 {
 line.push_back(field);
 field.clear();
 }
 break;

 case '\n':
 case '\r':
 if (inQuote == true)
 {
 field += *aChar;
 }
 else
 {
 if (newLine == false)
 {
 line.push_back(field);
 lines.push_back(line);
 field.clear();
 line.clear();
 newLine = true;
 }
 }
 break;

 default:
 newLine = false;
 field.push_back(*aChar);
 break;
 }

 aChar++;
 }

 if (field.size())
 line.push_back(field);

 if (line.size())
 lines.push_back(line);
 }
</code></pre>

blocks|key|1104818|text|如果你不想在你的项目中包含boost+(如果你要用它来进行CSV解析，那么它就相当大了……)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1104819|我很幸运地在这里进行了CSV解析：|1104820|http://www.zedwood.com/article/112/cpp-csv-parser|offset|length|1104821|它可以处理带引号的字段，但不能处理行内\n字符(对于大多数用途来说，这可能是很好的)。|1104822|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|1D|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|S|8|@]|9|@$F|T|G|U|1|V]]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|E]]]]

If you don't want to deal with including boost in your project (it is considerably large if all you are going to use it for is CSV parsing...)

I have had luck with the CSV parsing here:

<a href="http://www.zedwood.com/article/112/cpp-csv-parser" rel="nofollow">http://www.zedwood.com/article/112/cpp-csv-parser</a>

It handles quoted fields - but does not handle inline \n characters (which is probably fine for most uses).

blocks|key|115902|text|由于所有的CSV问题似乎都被重定向到了这里，我想我应该在这里发布我的答案。这个答案并没有直接回答发问者的问题。我希望能够读入一个已知为CSV格式的流，并且每个字段的类型也是已知的。当然，可以使用下面的方法将每个字段都视为字符串类型。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|115903|作为我希望如何使用CSV输入流的一个示例，请考虑以下输入(取自wikipedia's+page+on+CSV)：|offset|length|115904|const+char+input[]+=
"Year,Make,Model,Description,Price\n"
"1997,Ford,E350,\"ac,+abs,+moon\",3000.00\n"
"1999,Chevy,\"Venture+\"\"Extended+Edition\"\"\",\"\",4900.00\n"
"1999,Chevy,\"Venture+\"\"Extended+Edition,+Very+Large\"\"\",\"\",5000.00\n"
"1996,Jeep,Grand+Cherokee,\"MUST+SELL!\n\
air,+moon+roof,+loaded\",4799.00\n"
;|code-block|syntax|javascript|115905|然后，我希望能够像这样读取数据：|115906|std::istringstream+ss(input);
std::string+title[5];
int+year;
std::string+make,+model,+desc;
float+price;
csv_istream(ss)
++++>>+title[0]+>>+title[1]+>>+title[2]+>>+title[3]+>>+title[4];
while+(csv_istream(ss)
+++++++>>+year+>>+make+>>+model+>>+desc+>>+price)+{
++++//...do+something+with+the+record...
}|115907|这就是我最终得到的解决方案。|115908|struct+csv_istream+{
++++std::istream+&is_;
++++csv_istream+(std::istream+&is)+:+is_(is)+{}
++++void+scan_ws+()+const+{
++++++++while+(is_.good())+{
++++++++++++int+c+=+is_.peek();
++++++++++++if+(c+!=+'+'+&&+c+!=+'\t')+break;
++++++++++++is_.get();
++++++++}
++++}
++++void+scan+(std::string+*s+=+0)+const+{
++++++++std::string+ws;
++++++++int+c+=+is_.get();
++++++++if+(is_.good())+{
++++++++++++do+{
++++++++++++++++if+(c+==+','+%7C%7C+c+==+'\n')+break;
++++++++++++++++if+(s)+{
++++++++++++++++++++ws+%2B=+c;
++++++++++++++++++++if+(c+!=+'+'+&&+c+!=+'\t')+{
++++++++++++++++++++++++*s+%2B=+ws;
++++++++++++++++++++++++ws.clear();
++++++++++++++++++++}
++++++++++++++++}
++++++++++++++++c+=+is_.get();
++++++++++++}+while+(is_.good());
++++++++++++if+(is_.eof())+is_.clear();
++++++++}
++++}
++++template+<typename+T,+bool>+struct+set_value+{
++++++++void+operator+()+(std::string+in,+T+&v)+const+{
++++++++++++std::istringstream(in)+>>+v;
++++++++}
++++};
++++template+<typename+T>+struct+set_value<T,+true>+{
++++++++template+<bool+SIGNED>+void+convert+(std::string+in,+T+&v)+const+{
++++++++++++if+(SIGNED)+v+=+::strtoll(in.c_str(),+0,+0);
++++++++++++else+v+=+::strtoull(in.c_str(),+0,+0);
++++++++}
++++++++void+operator+()+(std::string+in,+T+&v)+const+{
++++++++++++convert<is_signed_int<T>::val>(in,+v);
++++++++}
++++};
++++template+<typename+T>+const+csv_istream+&+operator+>>+(T+&v)+const+{
++++++++std::string+tmp;
++++++++scan(&tmp);
++++++++set_value<T,+is_int<T>::val>()(tmp,+v);
++++++++return+*this;
++++}
++++const+csv_istream+&+operator+>>+(std::string+&v)+const+{
++++++++v.clear();
++++++++scan_ws();
++++++++if+(is_.peek()+!=+'"')+scan(&v);
++++++++else+{
++++++++++++std::string+tmp;
++++++++++++is_.get();
++++++++++++std::getline(is_,+tmp,+'"');
++++++++++++while+(is_.peek()+==+'"')+{
++++++++++++++++v+%2B=+tmp;
++++++++++++++++v+%2B=+is_.get();
++++++++++++++++std::getline(is_,+tmp,+'"');
++++++++++++}
++++++++++++v+%2B=+tmp;
++++++++++++scan();
++++++++}
++++++++return+*this;
++++}
++++template+<typename+T>
++++const+csv_istream+&+operator+>>+(T+&(*manip)(T+&))+const+{
++++++++is_+>>+manip;
++++++++return+*this;
++++}
++++operator+bool+()+const+{+return+!is_.fail();+}
};|115909|使用C%2B%2B11中新的integral+C%2B%2B11模板可以简化以下帮助程序：|115910|template+<typename+T>+struct+is_signed_int+{+enum+{+val+=+false+};+};
template+<>+struct+is_signed_int<short>+{+enum+{+val+=+true};+};
template+<>+struct+is_signed_int<int>+{+enum+{+val+=+true};+};
template+<>+struct+is_signed_int<long>+{+enum+{+val+=+true};+};
template+<>+struct+is_signed_int<long+long>+{+enum+{+val+=+true};+};

template+<typename+T>+struct+is_unsigned_int+{+enum+{+val+=+false+};+};
template+<>+struct+is_unsigned_int<unsigned+short>+{+enum+{+val+=+true};+};
template+<>+struct+is_unsigned_int<unsigned+int>+{+enum+{+val+=+true};+};
template+<>+struct+is_unsigned_int<unsigned+long>+{+enum+{+val+=+true};+};
template+<>+struct+is_unsigned_int<unsigned+long+long>+{+enum+{+val+=+true};+};

template+<typename+T>+struct+is_int+{
++++enum+{+val+=+(is_signed_int<T>::val+%7C%7C+is_unsigned_int<T>::val)+};
};|115911|Try+it+online!|115912|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/Comma-separated_values|1|https://tio.run/##rVZtT@NGEP7uXzG4UrDpFuXK0VNev/ToqRVUlaAnVQRFxt6EFc6u5d2YIi6/nc6sHbKOHTig5iWb3Zlnnnn1xln20zyOH38QMk6XCYehUNrkPFqMvc2eXm95hi@yNDK4Z@4zLqMFh4sx4PEyNiD0VIu55MlUSAMPwOVygR9FlMIIZlGqOawG@OugtOsO9Y3KzXgbAiX5dwLg33vUUyXn79WHF0BejOVSviearvZw/QXeFth2rLfEuB3pTeHeDfXuyNuAe4BPDSGoJ/li3O/TwbdvDTrVUUjWVoPHCjnWxVSUrVTBa5P0@@utDqIM7LYrGGzLhNAnewGtHlZWvlACUxtHcnqnIQghVlKvPaDn7kak3NI/nCuVBGHoHNJDDsfoIUlknN8G4aB@PoMghr0R7ONPpwPlemL2Q7hGXrdb0mSHGxek5LnFtvINXROYtAONBLpN8q7Mnd5Aupy3rBHd3c4mamtj4@EIvWL7lNFyPZHtHq41dNgCZSOu4ccRxIPWw2ei2Y5Gz4FFdAPQtHkYpzzKt5NXz8HzOzsCaoVbyqhZJXTI1YyiTssGIbcQ2tqQwbVS6VMzam6m2EhL7kTG1o/KeB4ZlVO518pISAYX0CmahVRrOBQtWyoQMoTxGIoGx8FOkk16QyROA2bs2Ntokktw/vuXP08@j0v6yK3guXkNdYpuiRFCgWmyakalKXpwGE/xSxAy6OLvVlo4vSocjeXzKqv/JdCVg8PWkTkOSLkIXxXy0oo7GjsbcpjAoJ2MS9ksso1JmkBBB7ccGrV8li@CDecwQOE67ZybZS7hwNyIqjFLR17k6rJqY100O6ea721zrhzZdor4OERKz1yetgRaOqEtLjsm@JMO7qdCcjLMwEaEjNYFnUlRcRtV3JoDrqC51mDwdLKDyqvo1Odcu0EbtNY22JXk1jL9vvRjqQYHi0iKLKR12CwAdIckrczL9fYEbifN5gawVtijKM4ikaKHqIJXEnp7LiIhSfjBqwjfRDm2dbY0l1cw8vx/sALZWXTL2ZlKeMo@cx3nIjNCSfZXLmI@kb7nf@j1PrHfVJ6wk6PjLpv4UcwgutYMFkrJic@Out3uYbe7Fu6xX294cY@CX7lEdhwm/sQ/@ddwmeAF7iQRZID2UNf@@9h7AwCDrzy/h9Mon3MX7LjO5hf2B@cZ@5JHMgHEzdUt5yh59vf5BZyfnJ7uTeTEi0ReugO5UjOGF8wITRG1T71ehYb3yubbBbQObESxsmodJ0zKL4@vBh4l4h4DXT9fUNTRIoUdEoz7wJuhUQMZxX3gObUVaB3aIsByKWG7V5v1B2f9s7M@ctYfkUbVsW24JTRxLCvylttP4kYLYkefllnoXmxjtTQwHILfJ@XRpU9fLA5tXvlbDW0lCb6StJaekSQCa1FLZrcscaxELd3dktaLStSuS1lMMN7kPW/1@B8^0|0|V|N|0|0|0|0|0|0|0|0|0|0|E|1|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|19|8|@]|9|@$D|1A|E|1B|1|1C]]|A|$]]|$1|F|3|G|5|H|7|1D|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|1E|8|@]|9|@]|A|$]]|$1|M|3|N|5|H|7|1F|8|@]|9|@]|A|$I|J]]|$1|O|3|P|5|6|7|1G|8|@]|9|@]|A|$]]|$1|Q|3|R|5|H|7|1H|8|@]|9|@]|A|$I|J]]|$1|S|3|T|5|6|7|1I|8|@]|9|@]|A|$]]|$1|U|3|V|5|H|7|1J|8|@]|9|@]|A|$I|J]]|$1|W|3|X|5|6|7|1K|8|@]|9|@$D|1L|E|1M|1|1N]]|A|$]]|$1|Y|3|-4|5|6|7|1O|8|@]|9|@]|A|$]]]|Z|$10|$5|11|12|13|A|$14|15]]|16|$5|11|12|13|A|$14|17]]]]

As all the CSV questions seem to get redirected here, I thought I'd post my answer here. This answer does not directly address the asker's question. I wanted to be able to read in a stream that is known to be in CSV format, and also the types of each field was already known. Of course, the method below could be used to treat every field to be a string type.

As an example of how I wanted to be able to use a CSV input stream, consider the following input (taken from <a href="http://en.wikipedia.org/wiki/Comma-separated_values" rel="nofollow noreferrer">wikipedia's page on CSV</a>):

<pre><code>const char input[] =
"Year,Make,Model,Description,Price\n"
"1997,Ford,E350,\"ac, abs, moon\",3000.00\n"
"1999,Chevy,\"Venture \"\"Extended Edition\"\"\",\"\",4900.00\n"
"1999,Chevy,\"Venture \"\"Extended Edition, Very Large\"\"\",\"\",5000.00\n"
"1996,Jeep,Grand Cherokee,\"MUST SELL!\n\
air, moon roof, loaded\",4799.00\n"
;
</code></pre>

Then, I wanted to be able to read in the data like this:

<pre><code>std::istringstream ss(input);
std::string title[5];
int year;
std::string make, model, desc;
float price;
csv_istream(ss)
 &gt;&gt; title[0] &gt;&gt; title[1] &gt;&gt; title[2] &gt;&gt; title[3] &gt;&gt; title[4];
while (csv_istream(ss)
 &gt;&gt; year &gt;&gt; make &gt;&gt; model &gt;&gt; desc &gt;&gt; price) {
 //...do something with the record...
}
</code></pre>

This was the solution I ended up with.

<pre><code>struct csv_istream {
 std::istream &amp;is_;
 csv_istream (std::istream &amp;is) : is_(is) {}
 void scan_ws () const {
 while (is_.good()) {
 int c = is_.peek();
 if (c != ' ' &amp;&amp; c != '\t') break;
 is_.get();
 }
 }
 void scan (std::string *s = 0) const {
 std::string ws;
 int c = is_.get();
 if (is_.good()) {
 do {
 if (c == ',' || c == '\n') break;
 if (s) {
 ws += c;
 if (c != ' ' &amp;&amp; c != '\t') {
 *s += ws;
 ws.clear();
 }
 }
 c = is_.get();
 } while (is_.good());
 if (is_.eof()) is_.clear();
 }
 }
 template &lt;typename T, bool&gt; struct set_value {
 void operator () (std::string in, T &amp;v) const {
 std::istringstream(in) &gt;&gt; v;
 }
 };
 template &lt;typename T&gt; struct set_value&lt;T, true&gt; {
 template &lt;bool SIGNED&gt; void convert (std::string in, T &amp;v) const {
 if (SIGNED) v = ::strtoll(in.c_str(), 0, 0);
 else v = ::strtoull(in.c_str(), 0, 0);
 }
 void operator () (std::string in, T &amp;v) const {
 convert&lt;is_signed_int&lt;T&gt;::val&gt;(in, v);
 }
 };
 template &lt;typename T&gt; const csv_istream &amp; operator &gt;&gt; (T &amp;v) const {
 std::string tmp;
 scan(&amp;tmp);
 set_value&lt;T, is_int&lt;T&gt;::val&gt;()(tmp, v);
 return *this;
 }
 const csv_istream &amp; operator &gt;&gt; (std::string &amp;v) const {
 v.clear();
 scan_ws();
 if (is_.peek() != '"') scan(&amp;v);
 else {
 std::string tmp;
 is_.get();
 std::getline(is_, tmp, '"');
 while (is_.peek() == '"') {
 v += tmp;
 v += is_.get();
 std::getline(is_, tmp, '"');
 }
 v += tmp;
 scan();
 }
 return *this;
 }
 template &lt;typename T&gt;
 const csv_istream &amp; operator &gt;&gt; (T &amp;(*manip)(T &amp;)) const {
 is_ &gt;&gt; manip;
 return *this;
 }
 operator bool () const { return !is_.fail(); }
};
</code></pre>

With the following helpers that may be simplified by the new integral traits templates in C++11:

<pre><code>template &lt;typename T&gt; struct is_signed_int { enum { val = false }; };
template &lt;&gt; struct is_signed_int&lt;short&gt; { enum { val = true}; };
template &lt;&gt; struct is_signed_int&lt;int&gt; { enum { val = true}; };
template &lt;&gt; struct is_signed_int&lt;long&gt; { enum { val = true}; };
template &lt;&gt; struct is_signed_int&lt;long long&gt; { enum { val = true}; };

template &lt;typename T&gt; struct is_unsigned_int { enum { val = false }; };
template &lt;&gt; struct is_unsigned_int&lt;unsigned short&gt; { enum { val = true}; };
template &lt;&gt; struct is_unsigned_int&lt;unsigned int&gt; { enum { val = true}; };
template &lt;&gt; struct is_unsigned_int&lt;unsigned long&gt; { enum { val = true}; };
template &lt;&gt; struct is_unsigned_int&lt;unsigned long long&gt; { enum { val = true}; };

template &lt;typename T&gt; struct is_int {
 enum { val = (is_signed_int&lt;T&gt;::val || is_unsigned_int&lt;T&gt;::val) };
};
</code></pre>

<a href="https://tio.run/##rVZtT@NGEP7uXzG4UrDpFuXK0VNev/ToqRVUlaAnVQRFxt6EFc6u5d2YIi6/nc6sHbKOHTig5iWb3Zlnnnn1xln20zyOH38QMk6XCYehUNrkPFqMvc2eXm95hi@yNDK4Z@4zLqMFh4sx4PEyNiD0VIu55MlUSAMPwOVygR9FlMIIZlGqOawG@OugtOsO9Y3KzXgbAiX5dwLg33vUUyXn79WHF0BejOVSviearvZw/QXeFth2rLfEuB3pTeHeDfXuyNuAe4BPDSGoJ/li3O/TwbdvDTrVUUjWVoPHCjnWxVSUrVTBa5P0@@utDqIM7LYrGGzLhNAnewGtHlZWvlACUxtHcnqnIQghVlKvPaDn7kak3NI/nCuVBGHoHNJDDsfoIUlknN8G4aB@PoMghr0R7ONPpwPlemL2Q7hGXrdb0mSHGxek5LnFtvINXROYtAONBLpN8q7Mnd5Aupy3rBHd3c4mamtj4@EIvWL7lNFyPZHtHq41dNgCZSOu4ccRxIPWw2ei2Y5Gz4FFdAPQtHkYpzzKt5NXz8HzOzsCaoVbyqhZJXTI1YyiTssGIbcQ2tqQwbVS6VMzam6m2EhL7kTG1o/KeB4ZlVO518pISAYX0CmahVRrOBQtWyoQMoTxGIoGx8FOkk16QyROA2bs2Ntokktw/vuXP08@j0v6yK3guXkNdYpuiRFCgWmyakalKXpwGE/xSxAy6OLvVlo4vSocjeXzKqv/JdCVg8PWkTkOSLkIXxXy0oo7GjsbcpjAoJ2MS9ksso1JmkBBB7ccGrV8li@CDecwQOE67ZybZS7hwNyIqjFLR17k6rJqY100O6ea721zrhzZdor4OERKz1yetgRaOqEtLjsm@JMO7qdCcjLMwEaEjNYFnUlRcRtV3JoDrqC51mDwdLKDyqvo1Odcu0EbtNY22JXk1jL9vvRjqQYHi0iKLKR12CwAdIckrczL9fYEbifN5gawVtijKM4ikaKHqIJXEnp7LiIhSfjBqwjfRDm2dbY0l1cw8vx/sALZWXTL2ZlKeMo@cx3nIjNCSfZXLmI@kb7nf@j1PrHfVJ6wk6PjLpv4UcwgutYMFkrJic@Out3uYbe7Fu6xX294cY@CX7lEdhwm/sQ/@ddwmeAF7iQRZID2UNf@@9h7AwCDrzy/h9Mon3MX7LjO5hf2B@cZ@5JHMgHEzdUt5yh59vf5BZyfnJ7uTeTEi0ReugO5UjOGF8wITRG1T71ehYb3yubbBbQObESxsmodJ0zKL4@vBh4l4h4DXT9fUNTRIoUdEoz7wJuhUQMZxX3gObUVaB3aIsByKWG7V5v1B2f9s7M@ctYfkUbVsW24JTRxLCvylttP4kYLYkefllnoXmxjtTQwHILfJ@XRpU9fLA5tXvlbDW0lCb6StJaekSQCa1FLZrcscaxELd3dktaLStSuS1lMMN7kPW/1@B8" rel="nofollow noreferrer" title="C++ (gcc) – Try It Online">Try it online!</a>

blocks|key|4321644|text|可以在以下位置找到另一个CSV+I/O库：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4321645|http://code.google.com/p/fast-cpp-csv-parser/|offset|length|4321646|#include+"csv.h"

int+main(){
++io::CSVReader<3>+in("ram.csv");
++in.read_header(io::ignore_extra_column,+"vendor",+"size",+"speed");
++std::string+vendor;+int+size;+double+speed;
++while(in.read_row(vendor,+size,+speed)){
++++//+do+stuff+with+the+data
++}
}|code-block|syntax|javascript|4321647|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|19|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|S|8|@]|9|@$D|T|E|U|1|V]]|A|$]]|$1|F|3|G|5|H|7|W|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|C]]]]

Another CSV I/O library can be found here:

<a href="http://code.google.com/p/fast-cpp-csv-parser/" rel="noreferrer">http://code.google.com/p/fast-cpp-csv-parser/</a>

<pre><code>#include "csv.h"

int main(){
 io::CSVReader&lt;3&gt; in("ram.csv");
 in.read_header(io::ignore_extra_column, "vendor", "size", "speed");
 std::string vendor; int size; double speed;
 while(in.read_row(vendor, size, speed)){
 // do stuff with the data
 }
}
</code></pre>

blocks|key|115031|text|下面是读取矩阵的代码，请注意，在matlab中还有一个csvwrite函数|type|unstyled|depth|inlineStyleRanges|entityRanges|data|115032|void+loadFromCSV(+const+std::string&+filename+)
{
++++std::ifstream+++++++file(+filename.c_str()+);
++++std::vector<+std::vector<std::string>+>+++matrix;
++++std::vector<std::string>+++row;
++++std::string++++++++++++++++line;
++++std::string++++++++++++++++cell;

++++while(+file+)
++++{
++++++++std::getline(file,line);
++++++++std::stringstream+lineStream(line);
++++++++row.clear();

++++++++while(+std::getline(+lineStream,+cell,+','+)+)
++++++++++++row.push_back(+cell+);

++++++++if(+!row.empty()+)
++++++++++++matrix.push_back(+row+);
++++}

++++for(+int+i=0;+i<int(matrix.size());+i%2B%2B+)
++++{
++++++++for(+int+j=0;+j<int(matrix[i].size());+j%2B%2B+)
++++++++++++std::cout+<<+matrix[i][j]+<<+"+";

++++++++std::cout+<<+std::endl;
++++}
}|code-block|syntax|javascript|115033|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here is code for reading a matrix, note you also have a csvwrite function in matlab

<pre><code>void loadFromCSV( const std::string&amp; filename )
{
 std::ifstream file( filename.c_str() );
 std::vector&lt; std::vector&lt;std::string&gt; &gt; matrix;
 std::vector&lt;std::string&gt; row;
 std::string line;
 std::string cell;

 while( file )
 {
 std::getline(file,line);
 std::stringstream lineStream(line);
 row.clear();

 while( std::getline( lineStream, cell, ',' ) )
 row.push_back( cell );

 if( !row.empty() )
 matrix.push_back( row );
 }

 for( int i=0; i&lt;int(matrix.size()); i++ )
 {
 for( int j=0; j&lt;int(matrix[i].size()); j++ )
 std::cout &lt;&lt; matrix[i][j] &lt;&lt; " ";

 std::cout &lt;&lt; std::endl;
 }
}
</code></pre>

blocks|key|1105035|text|这是一个旧的线程，但它仍然在搜索结果的顶部，所以我使用std::stringstream和我在这里找到的Yves+Baume的一个简单的字符串替换方法添加了我的解决方案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105036|下面的示例将逐行读取文件，忽略以//开头的注释行，并将其他行解析为字符串、整型和双精度的组合。Stringstream执行解析，但希望字段由空格分隔，因此我首先使用stringreplace将逗号转换为空格。它可以处理制表符，但不能处理带引号的字符串。|1105037|错误或丢失的输入将被忽略，这可能是好的也可能不是好的，这取决于您的环境。|1105038|#include+<string>
#include+<sstream>
#include+<fstream>

void+StringReplace(std::string&+str,+const+std::string&+oldStr,+const+std::string&+newStr)
//+code+by++Yves+Baumes
//+http://stackoverflow.com/questions/1494399/how-do-i-search-find-and-replace-in-a-standard-string
{
++size_t+pos+=+0;
++while((pos+=+str.find(oldStr,+pos))+!=+std::string::npos)
++{
+++++str.replace(pos,+oldStr.length(),+newStr);
+++++pos+%2B=+newStr.length();
++}
}

void+LoadCSV(std::string+&filename)+{
+++std::ifstream+stream(filename);
+++std::string+in_line;
+++std::string+Field;
+++std::string+Chan;
+++int+ChanType;
+++double+Scale;
+++int+Import;
+++while+(std::getline(stream,+in_line))+{
++++++StringReplace(in_line,+",",+"+");
++++++std::stringstream+line(in_line);
++++++line+>>+Field+>>+Chan+>>+ChanType+>>+Scale+>>+Import;
++++++if+(Field.substr(0,2)!="//")+{
+++++++++//+do+your+stuff+
+++++++++//+this+is+CBuilder+code+for+demonstration,+sorry
+++++++++ShowMessage((String)Field.c_str()+%2B+"\n"+%2B+Chan.c_str()+%2B+"\n"+%2B+IntToStr(ChanType)+%2B+"\n"+%2BFloatToStr(Scale)+%2B+"\n"+%2BIntToStr(Import));
++++++}
+++}
}|code-block|syntax|javascript|1105039|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

This is an old thread but its still at the top of search results, so I'm adding my solution using std::stringstream and a simple string replace method by Yves Baumes I found here. 

The following example will read a file line by line, ignore comment lines starting with // and parse the other lines into a combination of strings, ints and doubles. Stringstream does the parsing, but expects fields to be delimited by whitespace, so I use stringreplace to turn commas into spaces first. It handles tabs ok, but doesn't deal with quoted strings.

Bad or missing input is simply ignored, which may or may not be good, depending on your circumstance.

<pre><code>#include &lt;string&gt;
#include &lt;sstream&gt;
#include &lt;fstream&gt;

void StringReplace(std::string&amp; str, const std::string&amp; oldStr, const std::string&amp; newStr)
// code by Yves Baumes
// http://stackoverflow.com/questions/1494399/how-do-i-search-find-and-replace-in-a-standard-string
{
 size_t pos = 0;
 while((pos = str.find(oldStr, pos)) != std::string::npos)
 {
 str.replace(pos, oldStr.length(), newStr);
 pos += newStr.length();
 }
}

void LoadCSV(std::string &amp;filename) {
 std::ifstream stream(filename);
 std::string in_line;
 std::string Field;
 std::string Chan;
 int ChanType;
 double Scale;
 int Import;
 while (std::getline(stream, in_line)) {
 StringReplace(in_line, ",", " ");
 std::stringstream line(in_line);
 line &gt;&gt; Field &gt;&gt; Chan &gt;&gt; ChanType &gt;&gt; Scale &gt;&gt; Import;
 if (Field.substr(0,2)!="//") {
 // do your stuff 
 // this is CBuilder code for demonstration, sorry
 ShowMessage((String)Field.c_str() + "\n" + Chan.c_str() + "\n" + IntToStr(ChanType) + "\n" +FloatToStr(Scale) + "\n" +IntToStr(Import));
 }
 }
}
</code></pre>

blocks|key|4321839|text|值得一提的是，下面是我的实现。它处理wstring输入，但可以很容易地调整为string。它不处理字段中的换行符(我的应用程序也不处理，但添加它的支持并不太困难)，并且它不符合RFC中的"\r\n“行尾(假设您使用std::getline)，但它确实正确地处理了空格修剪和双引号(希望如此)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4321840|using+namespace+std;

//+trim+whitespaces+around+field+or+double-quotes,+remove+double-quotes+and+replace+escaped+double-quotes+(double+double-quotes)
wstring+trimquote(const+wstring&+str,+const+wstring&+whitespace,+const+wchar_t+quotChar)
{
++++wstring+ws;
++++wstring::size_type+strBegin+=+str.find_first_not_of(whitespace);
++++if+(strBegin+==+wstring::npos)
++++++++return+L"";

++++wstring::size_type+strEnd+=+str.find_last_not_of(whitespace);
++++wstring::size_type+strRange+=+strEnd+-+strBegin+%2B+1;

++++if((str[strBegin]+==+quotChar)+&&+(str[strEnd]+==+quotChar))
++++{
++++++++ws+=+str.substr(strBegin%2B1,+strRange-2);
++++++++strBegin+=+0;
++++++++while((strEnd+=+ws.find(quotChar,+strBegin))+!=+wstring::npos)
++++++++{
++++++++++++ws.erase(strEnd,+1);
++++++++++++strBegin+=+strEnd%2B1;
++++++++}

++++}
++++else
++++++++ws+=+str.substr(strBegin,+strRange);
++++return+ws;
}

pair<unsigned,+unsigned>+nextCSVQuotePair(const+wstring&+line,+const+wchar_t+quotChar,+unsigned+ofs+=+0)
{
++++pair<unsigned,+unsigned>+r;
++++r.first+=+line.find(quotChar,+ofs);
++++r.second+=+wstring::npos;
++++if(r.first+!=+wstring::npos)
++++{
++++++++r.second+=+r.first;
++++++++while(((r.second+=+line.find(quotChar,+r.second%2B1))+!=+wstring::npos)
++++++++++++&&+(line[r.second%2B1]+==+quotChar))+//+WARNING:+assumes+null-terminated+string+such+that+line[r.second%2B1]+always+exist
++++++++++++r.second%2B%2B;

++++}
++++return+r;
}

unsigned+parseLine(vector<wstring>&+fields,+const+wstring&+line)
{
++++unsigned+ofs,+ofs0,+np;
++++const+wchar_t+delim+=+L',';
++++const+wstring+whitespace+=+L"+\t\xa0\x3000\x2000\x2001\x2002\x2003\x2004\x2005\x2006\x2007\x2008\x2009\x200a\x202f\x205f";
++++const+wchar_t+quotChar+=+L'\"';
++++pair<unsigned,+unsigned>+quot;

++++fields.clear();

++++ofs+=+ofs0+=+0;
++++quot+=+nextCSVQuotePair(line,+quotChar);
++++while((np+=+line.find(delim,+ofs))+!=+wstring::npos)
++++{
++++++++if((np+>+quot.first)+&&+(np+<+quot.second))
++++++++{+//+skip+delimiter+inside+quoted+field
++++++++++++ofs+=+quot.second%2B1;
++++++++++++quot+=+nextCSVQuotePair(line,+quotChar,+ofs);
++++++++++++continue;
++++++++}
++++++++fields.push_back(+trimquote(line.substr(ofs0,+np-ofs0),+whitespace,+quotChar)+);
++++++++ofs+=+ofs0+=+np%2B1;
++++}
++++fields.push_back(+trimquote(line.substr(ofs0),+whitespace,+quotChar)+);

++++return+fields.size();
}|code-block|syntax|javascript|4321841|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

For what it is worth, here is my implementation. It deals with wstring input, but could be adjusted to string easily. It does not handle newline in fields (as my application does not either, but adding its support isn't too difficult) and it does not comply with "\r\n" end of line as per RFC (assuming you use std::getline), but it does handle whitespace trimming and double-quotes correctly (hopefully).

<pre><code>using namespace std;

// trim whitespaces around field or double-quotes, remove double-quotes and replace escaped double-quotes (double double-quotes)
wstring trimquote(const wstring&amp; str, const wstring&amp; whitespace, const wchar_t quotChar)
{
 wstring ws;
 wstring::size_type strBegin = str.find_first_not_of(whitespace);
 if (strBegin == wstring::npos)
 return L"";

 wstring::size_type strEnd = str.find_last_not_of(whitespace);
 wstring::size_type strRange = strEnd - strBegin + 1;

 if((str[strBegin] == quotChar) &amp;&amp; (str[strEnd] == quotChar))
 {
 ws = str.substr(strBegin+1, strRange-2);
 strBegin = 0;
 while((strEnd = ws.find(quotChar, strBegin)) != wstring::npos)
 {
 ws.erase(strEnd, 1);
 strBegin = strEnd+1;
 }

 }
 else
 ws = str.substr(strBegin, strRange);
 return ws;
}

pair&lt;unsigned, unsigned&gt; nextCSVQuotePair(const wstring&amp; line, const wchar_t quotChar, unsigned ofs = 0)
{
 pair&lt;unsigned, unsigned&gt; r;
 r.first = line.find(quotChar, ofs);
 r.second = wstring::npos;
 if(r.first != wstring::npos)
 {
 r.second = r.first;
 while(((r.second = line.find(quotChar, r.second+1)) != wstring::npos)
 &amp;&amp; (line[r.second+1] == quotChar)) // WARNING: assumes null-terminated string such that line[r.second+1] always exist
 r.second++;

 }
 return r;
}

unsigned parseLine(vector&lt;wstring&gt;&amp; fields, const wstring&amp; line)
{
 unsigned ofs, ofs0, np;
 const wchar_t delim = L',';
 const wstring whitespace = L" \t\xa0\x3000\x2000\x2001\x2002\x2003\x2004\x2005\x2006\x2007\x2008\x2009\x200a\x202f\x205f";
 const wchar_t quotChar = L'\"';
 pair&lt;unsigned, unsigned&gt; quot;

 fields.clear();

 ofs = ofs0 = 0;
 quot = nextCSVQuotePair(line, quotChar);
 while((np = line.find(delim, ofs)) != wstring::npos)
 {
 if((np &gt; quot.first) &amp;&amp; (np &lt; quot.second))
 { // skip delimiter inside quoted field
 ofs = quot.second+1;
 quot = nextCSVQuotePair(line, quotChar, ofs);
 continue;
 }
 fields.push_back( trimquote(line.substr(ofs0, np-ofs0), whitespace, quotChar) );
 ofs = ofs0 = np+1;
 }
 fields.push_back( trimquote(line.substr(ofs0), whitespace, quotChar) );

 return fields.size();
}
</code></pre>

blocks|key|1417347|text|这是Unicode+CSV解析器的另一个实现(使用wchar_t)。我写了一部分，乔纳森·莱弗勒写了其余的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1417348|注意:此解析器旨在尽可能地复制Excel的行为，特别是在导入损坏或格式错误的+CSV文件时。|offset|length|style|BOLD|1417349|这是最初的问题--+Parsing+CSV+file+with+multiline+fields+and+escaped+double+quotes|1417350|这是作为SSCCE的代码(简短、自包含、正确的示例)。|1417351|#include+<stdbool.h>
#include+<wchar.h>
#include+<wctype.h>

extern+const+wchar_t+*nextCsvField(const+wchar_t+*p,+wchar_t+sep,+bool+*newline);

//+Returns+a+pointer+to+the+start+of+the+next+field,
//+or+zero+if+this+is+the+last+field+in+the+CSV
//+p+is+the+start+position+of+the+field
//+sep+is+the+separator+used,+i.e.+comma+or+semicolon
//+newline+says+whether+the+field+ends+with+a+newline+or+with+a+comma
const+wchar_t+*nextCsvField(const+wchar_t+*p,+wchar_t+sep,+bool+*newline)
{
++++//+Parse+quoted+sequences
++++if+('"'+==+p[0])+{
++++++++p%2B%2B;
++++++++while+(1)+{
++++++++++++//+Find+next+double-quote
++++++++++++p+=+wcschr(p,+L'"');
++++++++++++//+If+we+don't+find+it+or+it's+the+last+symbol
++++++++++++//+then+this+is+the+last+field
++++++++++++if+(!p+%7C%7C+!p[1])
++++++++++++++++return+0;
++++++++++++//+Check+for+"",+it+is+an+escaped+double-quote
++++++++++++if+(p[1]+!=+'"')
++++++++++++++++break;
++++++++++++//+Skip+the+escaped+double-quote
++++++++++++p+%2B=+2;
++++++++}
++++}

++++//+Find+next+newline+or+comma.
++++wchar_t+newline_or_sep[4]+=+L"\n\r+";
++++newline_or_sep[2]+=+sep;
++++p+=+wcspbrk(p,+newline_or_sep);

++++//+If+no+newline+or+separator,+this+is+the+last+field.
++++if+(!p)
++++++++return+0;

++++//+Check+if+we+had+newline.
++++*newline+=+(p[0]+==+'\r'+%7C%7C+p[0]+==+'\n');

++++//+Handle+"\r\n",+otherwise+just+increment
++++if+(p[0]+==+'\r'+&&+p[1]+==+'\n')
++++++++p+%2B=+2;
++++else
++++++++p%2B%2B;

++++return+p;
}

static+wchar_t+*csvFieldData(const+wchar_t+*fld_s,+const+wchar_t+*fld_e,+wchar_t+*buffer,+size_t+buflen)
{
++++wchar_t+*dst+=+buffer;
++++wchar_t+*end+=+buffer+%2B+buflen+-+1;
++++const+wchar_t+*src+=+fld_s;

++++if+(*src+==+L'"')
++++{
++++++++const+wchar_t+*p+=+src+%2B+1;
++++++++while+(p+<+fld_e+&&+dst+<+end)
++++++++{
++++++++++++if+(p[0]+==+L'"'+&&+p%2B1+<+fld_s+&&+p[1]+==+L'"')
++++++++++++{
++++++++++++++++*dst%2B%2B+=+p[0];
++++++++++++++++p+%2B=+2;
++++++++++++}
++++++++++++else+if+(p[0]+==+L'"')
++++++++++++{
++++++++++++++++p%2B%2B;
++++++++++++++++break;
++++++++++++}
++++++++++++else
++++++++++++++++*dst%2B%2B+=+*p%2B%2B;
++++++++}
++++++++src+=+p;
++++}
++++while+(src+<+fld_e+&&+dst+<+end)
++++++++*dst%2B%2B+=+*src%2B%2B;
++++if+(dst+>=+end)
++++++++return+0;
++++*dst+=+L'\0';
++++return(buffer);
}

static+void+dissect(const+wchar_t+*line)
{
++++const+wchar_t+*start+=+line;
++++const+wchar_t+*next;
++++bool+++++eol;
++++wprintf(L"Input+%253zd:+[%25.*ls]\n",+wcslen(line),+wcslen(line)-1,+line);
++++while+((next+=+nextCsvField(start,+L',',+&eol))+!=+0)
++++{
++++++++wchar_t+buffer[1024];
++++++++wprintf(L"Raw+Field:+[%25.*ls]+(eol+=+%25d)\n",+(next+-+start+-+eol),+start,+eol);
++++++++if+(csvFieldData(start,+next-1,+buffer,+sizeof(buffer)/sizeof(buffer[0]))+!=+0)
++++++++++++wprintf(L"Field+%253zd:+[%25ls]\n",+wcslen(buffer),+buffer);
++++++++start+=+next;
++++}
}

static+const+wchar_t+multiline[]+=
+++L"First+field+of+first+row,\"This+field+is+multiline\n"
++++"\n"
++++"but+that's+OK+because+it's+enclosed+in+double+quotes,+and+this\n"
++++"is+an+escaped+\"\"+double+quote\"+but+this+one+\"\"+is+not\n"
++++"+++\"This+is+second+field+of+second+row,+but+it+is+not+multiline\n"
++++"+++because+it+doesn't+start+\n"
++++"+++with+an+immediate+double+quote\"\n"
++++;

int+main(void)
{
++++wchar_t+line[1024];

++++while+(fgetws(line,+sizeof(line)/sizeof(line[0]),+stdin))
++++++++dissect(line);
++++dissect(multiline);

++++return+0;
}|code-block|syntax|javascript|1417352|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/15520113/parsing-csv-file-with-multiline-fields-and-escaped-double-quotes^0|0|U|8|0|A|1S|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@$D|10|E|11|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|12|8|@]|9|@$D|13|E|14|1|15]]|A|$]]|$1|J|3|K|5|6|7|16|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|17|8|@]|9|@]|A|$O|P]]|$1|Q|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

Here is another implementation of a Unicode CSV parser (works with wchar_t). I wrote part of it, while Jonathan Leffler wrote the rest.

Note: This parser is aimed at replicating Excel's behavior as closely as possible, specifically when importing broken or malformed CSV files.

This is the original question - <a href="https://stackoverflow.com/questions/15520113/parsing-csv-file-with-multiline-fields-and-escaped-double-quotes">Parsing CSV file with multiline fields and escaped double quotes</a>

This is the code as a SSCCE (Short, Self-Contained, Correct Example).

<pre><code>#include &lt;stdbool.h&gt;
#include &lt;wchar.h&gt;
#include &lt;wctype.h&gt;

extern const wchar_t *nextCsvField(const wchar_t *p, wchar_t sep, bool *newline);

// Returns a pointer to the start of the next field,
// or zero if this is the last field in the CSV
// p is the start position of the field
// sep is the separator used, i.e. comma or semicolon
// newline says whether the field ends with a newline or with a comma
const wchar_t *nextCsvField(const wchar_t *p, wchar_t sep, bool *newline)
{
 // Parse quoted sequences
 if ('"' == p[0]) {
 p++;
 while (1) {
 // Find next double-quote
 p = wcschr(p, L'"');
 // If we don't find it or it's the last symbol
 // then this is the last field
 if (!p || !p[1])
 return 0;
 // Check for "", it is an escaped double-quote
 if (p[1] != '"')
 break;
 // Skip the escaped double-quote
 p += 2;
 }
 }

 // Find next newline or comma.
 wchar_t newline_or_sep[4] = L"\n\r ";
 newline_or_sep[2] = sep;
 p = wcspbrk(p, newline_or_sep);

 // If no newline or separator, this is the last field.
 if (!p)
 return 0;

 // Check if we had newline.
 *newline = (p[0] == '\r' || p[0] == '\n');

 // Handle "\r\n", otherwise just increment
 if (p[0] == '\r' &amp;&amp; p[1] == '\n')
 p += 2;
 else
 p++;

 return p;
}

static wchar_t *csvFieldData(const wchar_t *fld_s, const wchar_t *fld_e, wchar_t *buffer, size_t buflen)
{
 wchar_t *dst = buffer;
 wchar_t *end = buffer + buflen - 1;
 const wchar_t *src = fld_s;

 if (*src == L'"')
 {
 const wchar_t *p = src + 1;
 while (p &lt; fld_e &amp;&amp; dst &lt; end)
 {
 if (p[0] == L'"' &amp;&amp; p+1 &lt; fld_s &amp;&amp; p[1] == L'"')
 {
 *dst++ = p[0];
 p += 2;
 }
 else if (p[0] == L'"')
 {
 p++;
 break;
 }
 else
 *dst++ = *p++;
 }
 src = p;
 }
 while (src &lt; fld_e &amp;&amp; dst &lt; end)
 *dst++ = *src++;
 if (dst &gt;= end)
 return 0;
 *dst = L'\0';
 return(buffer);
}

static void dissect(const wchar_t *line)
{
 const wchar_t *start = line;
 const wchar_t *next;
 bool eol;
 wprintf(L"Input %3zd: [%.*ls]\n", wcslen(line), wcslen(line)-1, line);
 while ((next = nextCsvField(start, L',', &amp;eol)) != 0)
 {
 wchar_t buffer[1024];
 wprintf(L"Raw Field: [%.*ls] (eol = %d)\n", (next - start - eol), start, eol);
 if (csvFieldData(start, next-1, buffer, sizeof(buffer)/sizeof(buffer[0])) != 0)
 wprintf(L"Field %3zd: [%ls]\n", wcslen(buffer), buffer);
 start = next;
 }
}

static const wchar_t multiline[] =
 L"First field of first row,\"This field is multiline\n"
 "\n"
 "but that's OK because it's enclosed in double quotes, and this\n"
 "is an escaped \"\" double quote\" but this one \"\" is not\n"
 " \"This is second field of second row, but it is not multiline\n"
 " because it doesn't start \n"
 " with an immediate double quote\"\n"
 ;

int main(void)
{
 wchar_t line[1024];

 while (fgetws(line, sizeof(line)/sizeof(line[0]), stdin))
 dissect(line);
 dissect(multiline);

 return 0;
}
</code></pre>

blocks|key|4321918|text|如果你只需要加载一个双精度的数据文件(没有整数，没有文本)，这里有一个现成的函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4321919|#include+<sstream>
#include+<fstream>
#include+<iterator>
#include+<string>
#include+<vector>
#include+<algorithm>

using+namespace+std;

/**
+*+Parse+a+CSV+data+file+and+fill+the+2d+STL+vector+"data".
+*+Limits:+only+"pure+datas"+of+doubles,+not+encapsulated+by+"+and+without+\n+inside.
+*+Further+no+formatting+in+the+data+(e.g.+scientific+notation)
+*+It+however+handles+both+dots+and+commas+as+decimal+separators+and+removes+thousand+separator.
+*+
+*+returnCodes[0]:+file+access+0->+ok+1->+not+able+to+read;+2->+decimal+separator+equal+to+comma+separator
+*+returnCodes[1]:+number+of+records
+*+returnCodes[2]:+number+of+fields.+-1+If+rows+have+different+field+size
+*+
+*/
vector<int>
readCsvData+(vector+<vector+<double>>&+data,+const+string&+filename,+const+string&+delimiter,+const+string&+decseparator){

+int+vv[3]+=+{+0,0,0+};
+vector<int>+returnCodes(&vv[0],+&vv[0]%2B3);

+string+rowstring,+stringtoken;
+double+doubletoken;
+int+rowcount=0;
+int+fieldcount=0;
+data.clear();

+ifstream+iFile(filename,+ios_base::in);
+if+(!iFile.is_open()){
+++returnCodes[0]+=+1;
+++return+returnCodes;
+}
+while+(getline(iFile,+rowstring))+{
++++if+(rowstring=="")+continue;+//+empty+line
++++rowcount+%2B%2B;+//let's+start+with+1
++++if(delimiter+==+decseparator){
++++++returnCodes[0]+=+2;
++++++return+returnCodes;
++++}
++++if(decseparator+!=+"."){
+++++//+remove+dots+(used+as+thousand+separators)
+++++string::iterator+end_pos+=+remove(rowstring.begin(),+rowstring.end(),+'.');
+++++rowstring.erase(end_pos,+rowstring.end());
+++++//+replace+decimal+separator+with+dots.
+++++replace(rowstring.begin(),+rowstring.end(),decseparator.c_str()[0],+'.');+
++++}+else+{
+++++//+remove+commas+(used+as+thousand+separators)
+++++string::iterator+end_pos+=+remove(rowstring.begin(),+rowstring.end(),+',');
+++++rowstring.erase(end_pos,+rowstring.end());
++++}
++++//+tokenize..
++++vector<double>+tokens;
++++//+Skip+delimiters+at+beginning.
++++string::size_type+lastPos+=+rowstring.find_first_not_of(delimiter,+0);
++++//+Find+first+"non-delimiter".
++++string::size_type+pos+++++=+rowstring.find_first_of(delimiter,+lastPos);
++++while+(string::npos+!=+pos+%7C%7C+string::npos+!=+lastPos){
++++++++//+Found+a+token,+convert+it+to+double+add+it+to+the+vector.
++++++++stringtoken+=+rowstring.substr(lastPos,+pos+-+lastPos);
++++++++if+(stringtoken+==+"")+{
++++++tokens.push_back(0.0);
++++}+else+{
++++++++++istringstream+totalSString(stringtoken);
++++++totalSString+>>+doubletoken;
++++++tokens.push_back(doubletoken);
++++}+++++
++++++++//+Skip+delimiters.++Note+the+"not_of"
++++++++lastPos+=+rowstring.find_first_not_of(delimiter,+pos);
++++++++//+Find+next+"non-delimiter"
++++++++pos+=+rowstring.find_first_of(delimiter,+lastPos);
++++}
++++if(rowcount+==+1){
++++++fieldcount+=+tokens.size();
++++++returnCodes[2]+=+tokens.size();
++++}+else+{
++++++if+(+tokens.size()+!=+fieldcount){
++++returnCodes[2]+=+-1;
++++++}
++++}
++++data.push_back(tokens);
+}
+iFile.close();
+returnCodes[1]+=+rowcount;
+return+returnCodes;
}|code-block|syntax|javascript|4321920|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here is a ready-to use function if all you need is to load a data file of doubles (no integers, no text).

<pre><code>#include &lt;sstream&gt;
#include &lt;fstream&gt;
#include &lt;iterator&gt;
#include &lt;string&gt;
#include &lt;vector&gt;
#include &lt;algorithm&gt;

using namespace std;

/**
 * Parse a CSV data file and fill the 2d STL vector "data".
 * Limits: only "pure datas" of doubles, not encapsulated by " and without \n inside.
 * Further no formatting in the data (e.g. scientific notation)
 * It however handles both dots and commas as decimal separators and removes thousand separator.
 * 
 * returnCodes[0]: file access 0-&gt; ok 1-&gt; not able to read; 2-&gt; decimal separator equal to comma separator
 * returnCodes[1]: number of records
 * returnCodes[2]: number of fields. -1 If rows have different field size
 * 
 */
vector&lt;int&gt;
readCsvData (vector &lt;vector &lt;double&gt;&gt;&amp; data, const string&amp; filename, const string&amp; delimiter, const string&amp; decseparator){

 int vv[3] = { 0,0,0 };
 vector&lt;int&gt; returnCodes(&amp;vv[0], &amp;vv[0]+3);

 string rowstring, stringtoken;
 double doubletoken;
 int rowcount=0;
 int fieldcount=0;
 data.clear();

 ifstream iFile(filename, ios_base::in);
 if (!iFile.is_open()){
 returnCodes[0] = 1;
 return returnCodes;
 }
 while (getline(iFile, rowstring)) {
 if (rowstring=="") continue; // empty line
 rowcount ++; //let's start with 1
 if(delimiter == decseparator){
 returnCodes[0] = 2;
 return returnCodes;
 }
 if(decseparator != "."){
 // remove dots (used as thousand separators)
 string::iterator end_pos = remove(rowstring.begin(), rowstring.end(), '.');
 rowstring.erase(end_pos, rowstring.end());
 // replace decimal separator with dots.
 replace(rowstring.begin(), rowstring.end(),decseparator.c_str()[0], '.'); 
 } else {
 // remove commas (used as thousand separators)
 string::iterator end_pos = remove(rowstring.begin(), rowstring.end(), ',');
 rowstring.erase(end_pos, rowstring.end());
 }
 // tokenize..
 vector&lt;double&gt; tokens;
 // Skip delimiters at beginning.
 string::size_type lastPos = rowstring.find_first_not_of(delimiter, 0);
 // Find first "non-delimiter".
 string::size_type pos = rowstring.find_first_of(delimiter, lastPos);
 while (string::npos != pos || string::npos != lastPos){
 // Found a token, convert it to double add it to the vector.
 stringtoken = rowstring.substr(lastPos, pos - lastPos);
 if (stringtoken == "") {
 tokens.push_back(0.0);
 } else {
 istringstream totalSString(stringtoken);
 totalSString &gt;&gt; doubletoken;
 tokens.push_back(doubletoken);
 } 
 // Skip delimiters. Note the "not_of"
 lastPos = rowstring.find_first_not_of(delimiter, pos);
 // Find next "non-delimiter"
 pos = rowstring.find_first_of(delimiter, lastPos);
 }
 if(rowcount == 1){
 fieldcount = tokens.size();
 returnCodes[2] = tokens.size();
 } else {
 if ( tokens.size() != fieldcount){
 returnCodes[2] = -1;
 }
 }
 data.push_back(tokens);
 }
 iFile.close();
 returnCodes[1] = rowcount;
 return returnCodes;
}
</code></pre>

blocks|key|4321956|text|另一种快速简单的方法是使用Boost.Fusion+I/O|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4321957|#include+<iostream>
#include+<sstream>

#include+<boost/fusion/adapted/boost_tuple.hpp>
#include+<boost/fusion/sequence/io.hpp>

namespace+fusion+=+boost::fusion;

struct+CsvString
{
++++std::string+value;

++++//+Stop+reading+a+string+once+a+CSV+delimeter+is+encountered.
++++friend+std::istream&+operator>>(std::istream&+s,+CsvString&+v)+{
++++++++v.value.clear();
++++++++for(;;)+{
++++++++++++auto+c+=+s.peek();
++++++++++++if(std::istream::traits_type::eof()+==+c+%7C%7C+','+==+c+%7C%7C+'\n'+==+c)
++++++++++++++++break;
++++++++++++v.value.push_back(c);
++++++++++++s.get();
++++++++}
++++++++return+s;
++++}

++++friend+std::ostream&+operator<<(std::ostream&+s,+CsvString+const&+v)+{
++++++++return+s+<<+v.value;
++++}
};

int+main()+{
++++std::stringstream+input("abc,123,true,3.14\n"
++++++++++++++++++++++++++++"def,456,false,2.718\n");

++++typedef+boost::tuple<CsvString,+int,+bool,+double>+CsvRow;

++++using+fusion::operator<<;
++++std::cout+<<+std::boolalpha;

++++using+fusion::operator>>;
++++input+>>+std::boolalpha;
++++input+>>+fusion::tuple_open("")+>>+fusion::tuple_close("\n")+>>+fusion::tuple_delimiter(',');

++++for(CsvRow+row;+input+>>+row;)
++++++++std::cout+<<+row+<<+'\n';
}|code-block|syntax|javascript|4321958|输出：|4321959|(abc+123+true+3.14)
(def+456+false+2.718)|4321960|entityMap|0|LINK|mutability|MUTABLE|url|http://www.boost.org/doc/libs/1_55_0/libs/fusion/doc/html/fusion/sequence/operator/i_o.html^0|D|G|D|G|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|13|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

Another quick and easy way is to use <a href="http://www.boost.org/doc/libs/1_55_0/libs/fusion/doc/html/fusion/sequence/operator/i_o.html" rel="nofollow"><code>Boost.Fusion I/O</code></a>:

<pre><code>#include &lt;iostream&gt;
#include &lt;sstream&gt;

#include &lt;boost/fusion/adapted/boost_tuple.hpp&gt;
#include &lt;boost/fusion/sequence/io.hpp&gt;

namespace fusion = boost::fusion;

struct CsvString
{
 std::string value;

 // Stop reading a string once a CSV delimeter is encountered.
 friend std::istream&amp; operator&gt;&gt;(std::istream&amp; s, CsvString&amp; v) {
 v.value.clear();
 for(;;) {
 auto c = s.peek();
 if(std::istream::traits_type::eof() == c || ',' == c || '\n' == c)
 break;
 v.value.push_back(c);
 s.get();
 }
 return s;
 }

 friend std::ostream&amp; operator&lt;&lt;(std::ostream&amp; s, CsvString const&amp; v) {
 return s &lt;&lt; v.value;
 }
};

int main() {
 std::stringstream input("abc,123,true,3.14\n"
 "def,456,false,2.718\n");

 typedef boost::tuple&lt;CsvString, int, bool, double&gt; CsvRow;

 using fusion::operator&lt;&lt;;
 std::cout &lt;&lt; std::boolalpha;

 using fusion::operator&gt;&gt;;
 input &gt;&gt; std::boolalpha;
 input &gt;&gt; fusion::tuple_open("") &gt;&gt; fusion::tuple_close("\n") &gt;&gt; fusion::tuple_delimiter(',');

 for(CsvRow row; input &gt;&gt; row;)
 std::cout &lt;&lt; row &lt;&lt; '\n';
}
</code></pre>

Outputs:

<pre><code>(abc 123 true 3.14)
(def 456 false 2.718)
</code></pre>

blocks|key|1105290|text|你可以使用fopen，fscanf函数打开和读取.csv文件，但重要的是要用data.Simplest解析的方式来解析数据，使用delimiter.In大小写的.csv，分隔符是'，‘。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105291|假设您的data1.csv文件如下：|1105292|A,45,76,01
B,77,67,02
C,63,76,03
D,65,44,04|code-block|syntax|javascript|1105293|您可以将数据标记化并存储在char数组中，然后使用atoi()等函数进行适当的转换|1105294|FILE+*fp;
char+str1[10],+str2[10],+str3[10],+str4[10];

fp+=+fopen("G:\\data1.csv",+"r");
if(NULL+==+fp)
{
++++printf("\nError+in+opening+file.");
++++return+0;
}
while(EOF+!=+fscanf(fp,+"+%25[%5E,],+%25[%5E,],+%25[%5E,],+%25s,+%25s,+%25s,+%25s+",+str1,+str2,+str3,+str4))
{
++++printf("\n%25s+%25s+%25s+%25s",+str1,+str2,+str3,+str4);
}
fclose(fp);|1105295|%5E，，%5E+-it反转逻辑，表示匹配任何不包含逗号的字符串，然后是最后一个，表示匹配终止前一个字符串的逗号。|1105296|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

You can open and read .csv file using fopen ,fscanf functions ,but the important thing is to parse the data.Simplest way to parse the data using delimiter.In case of .csv , delimiter is ','.

Suppose your data1.csv file is as follows : 

<pre><code>A,45,76,01
B,77,67,02
C,63,76,03
D,65,44,04
</code></pre>

you can tokenize data and store in char array and later use atoi() etc function for appropriate conversions 

<pre><code>FILE *fp;
char str1[10], str2[10], str3[10], str4[10];

fp = fopen("G:\\data1.csv", "r");
if(NULL == fp)
{
 printf("\nError in opening file.");
 return 0;
}
while(EOF != fscanf(fp, " %[^,], %[^,], %[^,], %s, %s, %s, %s ", str1, str2, str3, str4))
{
 printf("\n%s %s %s %s", str1, str2, str3, str4);
}
fclose(fp);
</code></pre>

[^,], ^ -it inverts logic , means match any string that does not contain comma then last , says to match comma that terminated previous string.

blocks|key|1105342|text|我的版本只使用标准的C%2B%2B11库。它很好地应对了Excel+CSV引用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105343|spam+eggs,"foo,bar","""fizz+buzz"""
1.23,4.567,-8.00E%2B09|code-block|syntax|javascript|1105344|代码以有限状态机的形式编写，并且一次使用一个字符。我认为这更容易推理。|1105345|#include+<istream>
#include+<string>
#include+<vector>

enum+class+CSVState+{
++++UnquotedField,
++++QuotedField,
++++QuotedQuote
};

std::vector<std::string>+readCSVRow(const+std::string+&row)+{
++++CSVState+state+=+CSVState::UnquotedField;
++++std::vector<std::string>+fields+{""};
++++size_t+i+=+0;+//+index+of+the+current+field
++++for+(char+c+:+row)+{
++++++++switch+(state)+{
++++++++++++case+CSVState::UnquotedField:
++++++++++++++++switch+(c)+{
++++++++++++++++++++case+',':+//+end+of+field
++++++++++++++++++++++++++++++fields.push_back("");+i%2B%2B;
++++++++++++++++++++++++++++++break;
++++++++++++++++++++case+'"':+state+=+CSVState::QuotedField;
++++++++++++++++++++++++++++++break;
++++++++++++++++++++default:++fields[i].push_back(c);
++++++++++++++++++++++++++++++break;+}
++++++++++++++++break;
++++++++++++case+CSVState::QuotedField:
++++++++++++++++switch+(c)+{
++++++++++++++++++++case+'"':+state+=+CSVState::QuotedQuote;
++++++++++++++++++++++++++++++break;
++++++++++++++++++++default:++fields[i].push_back(c);
++++++++++++++++++++++++++++++break;+}
++++++++++++++++break;
++++++++++++case+CSVState::QuotedQuote:
++++++++++++++++switch+(c)+{
++++++++++++++++++++case+',':+//+,+after+closing+quote
++++++++++++++++++++++++++++++fields.push_back("");+i%2B%2B;
++++++++++++++++++++++++++++++state+=+CSVState::UnquotedField;
++++++++++++++++++++++++++++++break;
++++++++++++++++++++case+'"':+//+""+->+"
++++++++++++++++++++++++++++++fields[i].push_back('"');
++++++++++++++++++++++++++++++state+=+CSVState::QuotedField;
++++++++++++++++++++++++++++++break;
++++++++++++++++++++default:++//+end+of+quote
++++++++++++++++++++++++++++++state+=+CSVState::UnquotedField;
++++++++++++++++++++++++++++++break;+}
++++++++++++++++break;
++++++++}
++++}
++++return+fields;
}

///+Read+CSV+file,+Excel+dialect.+Accept+"quoted+fields+""with+quotes"""
std::vector<std::vector<std::string>>+readCSV(std::istream+&in)+{
++++std::vector<std::vector<std::string>>+table;
++++std::string+row;
++++while+(!in.eof())+{
++++++++std::getline(in,+row);
++++++++if+(in.bad()+%7C%7C+in.fail())+{
++++++++++++break;
++++++++}
++++++++auto+fields+=+readCSVRow(row);
++++++++table.push_back(fields);
++++}
++++return+table;
}|1105346|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

My version is not using anything but the standard C++11 library. It copes well with Excel CSV quotation:

<pre><code>spam eggs,"foo,bar","""fizz buzz"""
1.23,4.567,-8.00E+09
</code></pre>

The code is written as a finite-state machine and is consuming one character at a time. I think it's easier to reason about.

<pre><code>#include &lt;istream&gt;
#include &lt;string&gt;
#include &lt;vector&gt;

enum class CSVState {
 UnquotedField,
 QuotedField,
 QuotedQuote
};

std::vector&lt;std::string&gt; readCSVRow(const std::string &amp;row) {
 CSVState state = CSVState::UnquotedField;
 std::vector&lt;std::string&gt; fields {""};
 size_t i = 0; // index of the current field
 for (char c : row) {
 switch (state) {
 case CSVState::UnquotedField:
 switch (c) {
 case ',': // end of field
 fields.push_back(""); i++;
 break;
 case '"': state = CSVState::QuotedField;
 break;
 default: fields[i].push_back(c);
 break; }
 break;
 case CSVState::QuotedField:
 switch (c) {
 case '"': state = CSVState::QuotedQuote;
 break;
 default: fields[i].push_back(c);
 break; }
 break;
 case CSVState::QuotedQuote:
 switch (c) {
 case ',': // , after closing quote
 fields.push_back(""); i++;
 state = CSVState::UnquotedField;
 break;
 case '"': // "" -&gt; "
 fields[i].push_back('"');
 state = CSVState::QuotedField;
 break;
 default: // end of quote
 state = CSVState::UnquotedField;
 break; }
 break;
 }
 }
 return fields;
}

/// Read CSV file, Excel dialect. Accept "quoted fields ""with quotes"""
std::vector&lt;std::vector&lt;std::string&gt;&gt; readCSV(std::istream &amp;in) {
 std::vector&lt;std::vector&lt;std::string&gt;&gt; table;
 std::string row;
 while (!in.eof()) {
 std::getline(in, row);
 if (in.bad() || in.fail()) {
 break;
 }
 auto fields = readCSVRow(row);
 table.push_back(fields);
 }
 return table;
}
</code></pre>

blocks|key|4322057|text|您需要做的第一件事是确保该文件存在。要实现这一点，您只需尝试打开路径中的文件流。打开文件流之后，使用stream.fail()查看它是否如预期的那样工作。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4322058|bool+fileExists(string+fileName)
{

ifstream+test;

test.open(fileName.c_str());

if+(test.fail())
{
++++test.close();
++++return+false;
}
else
{
++++test.close();
++++return+true;
}
}|code-block|syntax|javascript|4322059|您还必须验证提供的文件是否为正确的文件类型。为此，您需要查看提供的文件路径，直到找到文件扩展名。一旦你有了文件扩展名，确保它是一个.csv文件。|4322060|bool+verifyExtension(string+filename)
{
int+period+=+0;

for+(unsigned+int+i+=+0;+i+<+filename.length();+i%2B%2B)
{
++++if+(filename[i]+==+'.')
++++++++period+=+i;
}

string+extension;

for+(unsigned+int+i+=+period;+i+<+filename.length();+i%2B%2B)
++++extension+%2B=+filename[i];

if+(extension+==+".csv")
++++return+true;
else
++++return+false;
}|4322061|此函数将返回稍后在错误消息中使用的文件扩展名。|4322062|string+getExtension(string+filename)
{
int+period+=+0;

for+(unsigned+int+i+=+0;+i+<+filename.length();+i%2B%2B)
{
++++if+(filename[i]+==+'.')
++++++++period+=+i;
}

string+extension;

if+(period+!=+0)
{
++++for+(unsigned+int+i+=+period;+i+<+filename.length();+i%2B%2B)
++++++++extension+%2B=+filename[i];
}
else
++++extension+=+"NO+FILE";

return+extension;
}|4322063|此函数将实际调用上面创建的错误检查，然后解析文件。|4322064|void+parseFile(string+fileName)
{
++++if+(fileExists(fileName)+&&+verifyExtension(fileName))
++++{
++++++++ifstream+fs;
++++++++fs.open(fileName.c_str());
++++++++string+fileCommand;

++++++++while+(fs.good())
++++++++{
++++++++++++string+temp;

++++++++++++getline(fs,+fileCommand,+'\n');

++++++++++++for+(unsigned+int+i+=+0;+i+<+fileCommand.length();+i%2B%2B)
++++++++++++{
++++++++++++++++if+(fileCommand[i]+!=+',')
++++++++++++++++++++temp+%2B=+fileCommand[i];
++++++++++++++++else
++++++++++++++++++++temp+%2B=+"+";
++++++++++++}

++++++++++++if+(temp+!=+"\0")
++++++++++++{
++++++++++++++++//+Place+your+code+here+to+run+the+file.
++++++++++++}
++++++++}
++++++++fs.close();
++++}
++++else+if+(!fileExists(fileName))
++++{
++++++++cout+<<+"Error:+The+provided+file+does+not+exist:+"+<<+fileName+<<+endl;

++++++++if+(!verifyExtension(fileName))
++++++++{
++++++++++++if+(getExtension(fileName)+!=+"NO+FILE")
++++++++++++++++cout+<<+"\tCheck+the+file+extension."+<<+endl;
++++++++++++else
++++++++++++++++cout+<<+"\tThere+is+no+file+in+the+provided+path."+<<+endl;
++++++++}
++++}
++++else+if+(!verifyExtension(fileName))+
++++{
++++++++if+(getExtension(fileName)+!=+"NO+FILE")
++++++++++++cout+<<+"Incorrect+file+extension+provided:+"+<<+getExtension(fileName)+<<+endl;
++++++++else
++++++++++++cout+<<+"There+is+no+file+in+the+following+path:+"+<<+fileName+<<+endl;
++++}
}|4322065|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|Y|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

The first thing you need to do is make sure the file exists. To accomplish
this you just need to try and open the file stream at the path. After you
have opened the file stream use stream.fail() to see if it worked as expected,
or not.

<pre><code>bool fileExists(string fileName)
{

ifstream test;

test.open(fileName.c_str());

if (test.fail())
{
 test.close();
 return false;
}
else
{
 test.close();
 return true;
}
}
</code></pre>

You must also verify that the file provided is the correct type of file.
To accomplish this you need to look through the file path provided until 
you find the file extension. Once you have the file extension make sure
that it is a .csv file.

<pre><code>bool verifyExtension(string filename)
{
int period = 0;

for (unsigned int i = 0; i &lt; filename.length(); i++)
{
 if (filename[i] == '.')
 period = i;
}

string extension;

for (unsigned int i = period; i &lt; filename.length(); i++)
 extension += filename[i];

if (extension == ".csv")
 return true;
else
 return false;
}
</code></pre>

This function will return the file extension which is used later in an error message.

<pre><code>string getExtension(string filename)
{
int period = 0;

for (unsigned int i = 0; i &lt; filename.length(); i++)
{
 if (filename[i] == '.')
 period = i;
}

string extension;

if (period != 0)
{
 for (unsigned int i = period; i &lt; filename.length(); i++)
 extension += filename[i];
}
else
 extension = "NO FILE";

return extension;
}
</code></pre>

This function will actually call the error checks created above and then parse through the file.

<pre><code>void parseFile(string fileName)
{
 if (fileExists(fileName) &amp;&amp; verifyExtension(fileName))
 {
 ifstream fs;
 fs.open(fileName.c_str());
 string fileCommand;

 while (fs.good())
 {
 string temp;

 getline(fs, fileCommand, '\n');

 for (unsigned int i = 0; i &lt; fileCommand.length(); i++)
 {
 if (fileCommand[i] != ',')
 temp += fileCommand[i];
 else
 temp += " ";
 }

 if (temp != "\0")
 {
 // Place your code here to run the file.
 }
 }
 fs.close();
 }
 else if (!fileExists(fileName))
 {
 cout &lt;&lt; "Error: The provided file does not exist: " &lt;&lt; fileName &lt;&lt; endl;

 if (!verifyExtension(fileName))
 {
 if (getExtension(fileName) != "NO FILE")
 cout &lt;&lt; "\tCheck the file extension." &lt;&lt; endl;
 else
 cout &lt;&lt; "\tThere is no file in the provided path." &lt;&lt; endl;
 }
 }
 else if (!verifyExtension(fileName)) 
 {
 if (getExtension(fileName) != "NO FILE")
 cout &lt;&lt; "Incorrect file extension provided: " &lt;&lt; getExtension(fileName) &lt;&lt; endl;
 else
 cout &lt;&lt; "There is no file in the following path: " &lt;&lt; fileName &lt;&lt; endl;
 }
}
</code></pre>

blocks|key|1417437|text|我写了一个很好的解析CSV文件的方法，我想我应该把它作为答案添加进来：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1417438|#include+<algorithm>
#include+<fstream>
#include+<iostream>
#include+<stdlib.h>
#include+<stdio.h>

struct+CSVDict
{
++std::vector<+std::string+>+inputImages;
++std::vector<+double+>+inputLabels;
};

/**
\brief+Splits+the+string

\param+str+String+to+split
\param+delim+Delimiter+on+the+basis+of+which+splitting+is+to+be+done
\return+results+Output+in+the+form+of+vector+of+strings
*/
std::vector<std::string>+stringSplit(+const+std::string+&str,+const+std::string+&delim+)
{
++std::vector<std::string>+results;

++for+(size_t+i+=+0;+i+<+str.length();+i%2B%2B)
++{
++++std::string+tempString+=+"";
++++while+((str[i]+!=+*delim.c_str())+&&+(i+<+str.length()))
++++{
++++++tempString+%2B=+str[i];
++++++i%2B%2B;
++++}
++++results.push_back(tempString);
++}

++return+results;
}

/**
\brief+Parse+the+supplied+CSV+File+and+obtain+Row+and+Column+information.+

Assumptions:
1.+Header+information+is+in+first+row
2.+Delimiters+are+only+used+to+differentiate+cell+members

\param+csvFileName+The+full+path+of+the+file+to+parse
\param+inputColumns+The+string+of+input+columns+which+contain+the+data+to+be+used+for+further+processing
\param+inputLabels+The+string+of+input+labels+based+on+which+further+processing+is+to+be+done
\param+delim+The+delimiters+used+in+inputColumns+and+inputLabels
\return+Vector+of+Vector+of+strings:+Collection+of+rows+and+columns
*/
std::vector<+CSVDict+>+parseCSVFile(+const+std::string+&csvFileName,+const+std::string+&inputColumns,+const+std::string+&inputLabels,+const+std::string+&delim+)
{
++std::vector<+CSVDict+>+return_CSVDict;
++std::vector<+std::string+>+inputColumnsVec+=+stringSplit(inputColumns,+delim),+inputLabelsVec+=+stringSplit(inputLabels,+delim);
++std::vector<+std::vector<+std::string+>+>+returnVector;
++std::ifstream+inFile(csvFileName.c_str());
++int+row+=+0;
++std::vector<+size_t+>+inputColumnIndeces,+inputLabelIndeces;
++for+(std::string+line;+std::getline(inFile,+line,+'\n');)
++{
++++CSVDict+tempDict;
++++std::vector<+std::string+>+rowVec;
++++line.erase(std::remove(line.begin(),+line.end(),+'"'),+line.end());
++++rowVec+=+stringSplit(line,+delim);

++++//+for+the+first+row,+record+the+indeces+of+the+inputColumns+and+inputLabels
++++if+(row+==+0)
++++{
++++++for+(size_t+i+=+0;+i+<+rowVec.size();+i%2B%2B)
++++++{
++++++++for+(size_t+j+=+0;+j+<+inputColumnsVec.size();+j%2B%2B)
++++++++{
++++++++++if+(rowVec[i]+==+inputColumnsVec[j])
++++++++++{
++++++++++++inputColumnIndeces.push_back(i);
++++++++++}
++++++++}
++++++++for+(size_t+j+=+0;+j+<+inputLabelsVec.size();+j%2B%2B)
++++++++{
++++++++++if+(rowVec[i]+==+inputLabelsVec[j])
++++++++++{
++++++++++++inputLabelIndeces.push_back(i);
++++++++++}
++++++++}
++++++}
++++}
++++else
++++{
++++++for+(size_t+i+=+0;+i+<+inputColumnIndeces.size();+i%2B%2B)
++++++{
++++++++tempDict.inputImages.push_back(rowVec[inputColumnIndeces[i]]);
++++++}
++++++for+(size_t+i+=+0;+i+<+inputLabelIndeces.size();+i%2B%2B)
++++++{
++++++++double+test+=+std::atof(rowVec[inputLabelIndeces[i]].c_str());
++++++++tempDict.inputLabels.push_back(std::atof(rowVec[inputLabelIndeces[i]].c_str()));
++++++}
++++++return_CSVDict.push_back(tempDict);
++++}
++++row%2B%2B;
++}

++return+return_CSVDict;
}|code-block|syntax|javascript|1417439|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I wrote a nice way of parsing CSV files and I thought I should add it as an answer:

<pre><code>#include &lt;algorithm&gt;
#include &lt;fstream&gt;
#include &lt;iostream&gt;
#include &lt;stdlib.h&gt;
#include &lt;stdio.h&gt;

struct CSVDict
{
 std::vector&lt; std::string &gt; inputImages;
 std::vector&lt; double &gt; inputLabels;
};

/**
\brief Splits the string

\param str String to split
\param delim Delimiter on the basis of which splitting is to be done
\return results Output in the form of vector of strings
*/
std::vector&lt;std::string&gt; stringSplit( const std::string &amp;str, const std::string &amp;delim )
{
 std::vector&lt;std::string&gt; results;

 for (size_t i = 0; i &lt; str.length(); i++)
 {
 std::string tempString = "";
 while ((str[i] != *delim.c_str()) &amp;&amp; (i &lt; str.length()))
 {
 tempString += str[i];
 i++;
 }
 results.push_back(tempString);
 }

 return results;
}

/**
\brief Parse the supplied CSV File and obtain Row and Column information. 

Assumptions:
1. Header information is in first row
2. Delimiters are only used to differentiate cell members

\param csvFileName The full path of the file to parse
\param inputColumns The string of input columns which contain the data to be used for further processing
\param inputLabels The string of input labels based on which further processing is to be done
\param delim The delimiters used in inputColumns and inputLabels
\return Vector of Vector of strings: Collection of rows and columns
*/
std::vector&lt; CSVDict &gt; parseCSVFile( const std::string &amp;csvFileName, const std::string &amp;inputColumns, const std::string &amp;inputLabels, const std::string &amp;delim )
{
 std::vector&lt; CSVDict &gt; return_CSVDict;
 std::vector&lt; std::string &gt; inputColumnsVec = stringSplit(inputColumns, delim), inputLabelsVec = stringSplit(inputLabels, delim);
 std::vector&lt; std::vector&lt; std::string &gt; &gt; returnVector;
 std::ifstream inFile(csvFileName.c_str());
 int row = 0;
 std::vector&lt; size_t &gt; inputColumnIndeces, inputLabelIndeces;
 for (std::string line; std::getline(inFile, line, '\n');)
 {
 CSVDict tempDict;
 std::vector&lt; std::string &gt; rowVec;
 line.erase(std::remove(line.begin(), line.end(), '"'), line.end());
 rowVec = stringSplit(line, delim);

 // for the first row, record the indeces of the inputColumns and inputLabels
 if (row == 0)
 {
 for (size_t i = 0; i &lt; rowVec.size(); i++)
 {
 for (size_t j = 0; j &lt; inputColumnsVec.size(); j++)
 {
 if (rowVec[i] == inputColumnsVec[j])
 {
 inputColumnIndeces.push_back(i);
 }
 }
 for (size_t j = 0; j &lt; inputLabelsVec.size(); j++)
 {
 if (rowVec[i] == inputLabelsVec[j])
 {
 inputLabelIndeces.push_back(i);
 }
 }
 }
 }
 else
 {
 for (size_t i = 0; i &lt; inputColumnIndeces.size(); i++)
 {
 tempDict.inputImages.push_back(rowVec[inputColumnIndeces[i]]);
 }
 for (size_t i = 0; i &lt; inputLabelIndeces.size(); i++)
 {
 double test = std::atof(rowVec[inputLabelIndeces[i]].c_str());
 tempDict.inputLabels.push_back(std::atof(rowVec[inputLabelIndeces[i]].c_str()));
 }
 return_CSVDict.push_back(tempDict);
 }
 row++;
 }

 return return_CSVDict;
}
</code></pre>

blocks|key|1415294|text|可以使用std::regex。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1415295|根据文件的大小和可用内存，可以逐行读取，也可以完全在std::string中读取。|1415296|要使用read+the+file，可以使用：|1415297|std::ifstream+t("file.txt");
std::string+sin((std::istreambuf_iterator<char>(t)),
+++++++++++++++++std::istreambuf_iterator<char>());|code-block|syntax|javascript|1415298|然后你可以匹配它，它实际上可以根据你的需求进行定制。|1415299|std::regex+word_regex(",\\s]%2B");
auto+what+=+
++++std::sregex_iterator(sin.begin(),+sin.end(),+word_regex);
auto+wend+=+std::sregex_iterator();

std::vector<std::string>+v;
for+(;what!=wend+;+wend)+{
++++std::smatch+match+=+*what;
++++v.push_back(match.str());
}|1415300|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/2602013/read-whole-ascii-file-into-c-stdstring^0|4|A|0|Q|B|0|3|D|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|16|8|@]|D|@$9|17|A|18|1|19]]|E|$]]|$1|J|3|K|5|L|7|1A|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1B|8|@]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1C|8|@]|D|@]|E|$M|N]]|$1|S|3|-4|5|6|7|1D|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]]]

It is possible to use <code>std::regex</code> . 

Depending on the size of your file and the memory available to you , it is possible read it either line by line or entirely in an <code>std::string</code>. 

To <a href="https://stackoverflow.com/questions/2602013/read-whole-ascii-file-into-c-stdstring">read the file</a> one can use : 

<pre><code>std::ifstream t("file.txt");
std::string sin((std::istreambuf_iterator&lt;char&gt;(t)),
 std::istreambuf_iterator&lt;char&gt;());
</code></pre>

then you can match with this which is actually customizable to your needs.

<pre><code>std::regex word_regex(",\\s]+");
auto what = 
 std::sregex_iterator(sin.begin(), sin.end(), word_regex);
auto wend = std::sregex_iterator();

std::vector&lt;std::string&gt; v;
for (;what!=wend ; wend) {
 std::smatch match = *what;
 v.push_back(match.str());
}
</code></pre>

blocks|key|1105462|text|另一个类似于Loki+Astari's+answer的解决方案，在C%2B%2B11中。这里的行是给定类型的std::tuple。代码扫描一行，然后扫描直到每个分隔符，然后将值直接转换并转储到元组中(使用一点模板代码)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1105463|for+(auto+row+:+csv<std::string,+int,+float>(file,+','))+{
++++std::cout+<<+"first+col:+"+<<+std::get<0>(row)+<<+std::endl;
}|code-block|syntax|javascript|1105464|的优点：|BOLD|1105465|只有通过operator>>.才能将C%2B%2B11.|1105466|automatic类型转换为std::tuple<t1,+...>，所以|unordered-list-item|1105467|非常干净易用|1105468|1105469|1105470|缺少什么：|1105471|在CSV格式错误的情况下，|1105472|转义和引用|1105473|无错误处理。|1105474|1105475|主代码：|1105476|#include+<iterator>
#include+<sstream>
#include+<string>

namespace+csvtools+{
++++///+Read+the+last+element+of+the+tuple+without+calling+recursively
++++template+<std::size_t+idx,+class...+fields>
++++typename+std::enable_if<idx+>=+std::tuple_size<std::tuple<fields...>>::value+-+1>::type
++++read_tuple(std::istream+&in,+std::tuple<fields...>+&out,+const+char+delimiter)+{
++++++++std::string+cell;
++++++++std::getline(in,+cell,+delimiter);
++++++++std::stringstream+cell_stream(cell);
++++++++cell_stream+>>+std::get<idx>(out);
++++}

++++///+Read+the+@p+idx-th+element+of+the+tuple+and+then+calls+itself+with+@p+idx+%2B+1+to
++++///+read+the+next+element+of+the+tuple.+Automatically+falls+in+the+previous+case+when
++++///+reaches+the+last+element+of+the+tuple+thanks+to+enable_if
++++template+<std::size_t+idx,+class...+fields>
++++typename+std::enable_if<idx+<+std::tuple_size<std::tuple<fields...>>::value+-+1>::type
++++read_tuple(std::istream+&in,+std::tuple<fields...>+&out,+const+char+delimiter)+{
++++++++std::string+cell;
++++++++std::getline(in,+cell,+delimiter);
++++++++std::stringstream+cell_stream(cell);
++++++++cell_stream+>>+std::get<idx>(out);
++++++++read_tuple<idx+%2B+1,+fields...>(in,+out,+delimiter);
++++}
}

///+Iterable+csv+wrapper+around+a+stream.+@p+fields+the+list+of+types+that+form+up+a+row.
template+<class...+fields>
class+csv+{
++++std::istream+&_in;
++++const+char+_delim;
public:
++++typedef+std::tuple<fields...>+value_type;
++++class+iterator;

++++///+Construct+from+a+stream.
++++inline+csv(std::istream+&in,+const+char+delim)+:+_in(in),+_delim(delim)+{}

++++///+Status+of+the+underlying+stream
++++///+@{
++++inline+bool+good()+const+{
++++++++return+_in.good();
++++}
++++inline+const+std::istream+&underlying_stream()+const+{
++++++++return+_in;
++++}
++++///+@}

++++inline+iterator+begin();
++++inline+iterator+end();
private:

++++///+Reads+a+line+into+a+stringstream,+and+then+reads+the+line+into+a+tuple,+that+is+returned
++++inline+value_type+read_row()+{
++++++++std::string+line;
++++++++std::getline(_in,+line);
++++++++std::stringstream+line_stream(line);
++++++++std::tuple<fields...>+retval;
++++++++csvtools::read_tuple<0,+fields...>(line_stream,+retval,+_delim);
++++++++return+retval;
++++}
};

///+Iterator;+just+calls+recursively+@ref+csv::read_row+and+stores+the+result.
template+<class...+fields>
class+csv<fields...>::iterator+{
++++csv::value_type+_row;
++++csv+*_parent;
public:
++++typedef+std::input_iterator_tag+iterator_category;
++++typedef+csv::value_type+++++++++value_type;
++++typedef+std::size_t+++++++++++++difference_type;
++++typedef+csv::value_type+*+++++++pointer;
++++typedef+csv::value_type+&+++++++reference;

++++///+Construct+an+empty/end+iterator
++++inline+iterator()+:+_parent(nullptr)+{}
++++///+Construct+an+iterator+at+the+beginning+of+the+@p+parent+csv+object.
++++inline+iterator(csv+&parent)+:+_parent(parent.good()+?+&parent+:+nullptr)+{
++++++++%2B%2B(*this);
++++}

++++///+Read+one+row,+if+possible.+Set+to+end+if+parent+is+not+good+anymore.
++++inline+iterator+&operator%2B%2B()+{
++++++++if+(_parent+!=+nullptr)+{
++++++++++++_row+=+_parent->read_row();
++++++++++++if+(!_parent->good())+{
++++++++++++++++_parent+=+nullptr;
++++++++++++}
++++++++}
++++++++return+*this;
++++}

++++inline+iterator+operator%2B%2B(int)+{
++++++++iterator+copy+=+*this;
++++++++%2B%2B(*this);
++++++++return+copy;
++++}

++++inline+csv::value_type+const+&operator*()+const+{
++++++++return+_row;
++++}

++++inline+csv::value_type+const+*operator->()+const+{
++++++++return+&_row;
++++}

++++bool+operator==(iterator+const+&other)+{
++++++++return+(this+==+&other)+or+(_parent+==+nullptr+and+other._parent+==+nullptr);
++++}
++++bool+operator!=(iterator+const+&other)+{
++++++++return+not+(*this+==+other);
++++}
};

template+<class...+fields>
typename+csv<fields...>::iterator+csv<fields...>::begin()+{
++++return+iterator(*this);
}

template+<class...+fields>
typename+csv<fields...>::iterator+csv<fields...>::end()+{
++++return+iterator();
}|1105477|我在GitHub上放了一个很小的工作示例；我一直使用它来解析一些数字数据，它达到了它的目的。|1105478|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/1120224/1749822|1|https://github.com/LizardM4/ballin-octo-tribble/tree/master/csv^0|1E|A|6|K|0|0|0|0|4|0|4|A|0|E|J|0|0|0|0|0|5|0|0|0|0|0|0|0|2|6|1|0^^$0|@$1|2|3|4|5|6|7|1L|8|@$9|1M|A|1N|B|C]]|D|@$9|1O|A|1P|1|1Q]]|E|$]]|$1|F|3|G|5|H|7|1R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1S|8|@$9|1T|A|1U|B|M]]|D|@]|E|$]]|$1|N|3|O|5|6|7|1V|8|@$9|1W|A|1X|B|C]]|D|@]|E|$]]|$1|P|3|Q|5|R|7|1Y|8|@$9|1Z|A|20|B|C]]|D|@]|E|$]]|$1|S|3|T|5|R|7|21|8|@]|D|@]|E|$]]|$1|U|3|-4|5|6|7|22|8|@]|D|@]|E|$]]|$1|V|3|-4|5|6|7|23|8|@]|D|@]|E|$]]|$1|W|3|X|5|6|7|24|8|@$9|25|A|26|B|M]]|D|@]|E|$]]|$1|Y|3|Z|5|6|7|27|8|@]|D|@]|E|$]]|$1|10|3|11|5|R|7|28|8|@]|D|@]|E|$]]|$1|12|3|13|5|R|7|29|8|@]|D|@]|E|$]]|$1|14|3|-4|5|6|7|2A|8|@]|D|@]|E|$]]|$1|15|3|16|5|6|7|2B|8|@]|D|@]|E|$]]|$1|17|3|18|5|H|7|2C|8|@]|D|@]|E|$I|J]]|$1|19|3|1A|5|6|7|2D|8|@]|D|@$9|2E|A|2F|1|2G]]|E|$]]|$1|1B|3|-4|5|6|7|2H|8|@]|D|@]|E|$]]]|1C|$1D|$5|1E|1F|1G|E|$1H|1I]]|1J|$5|1E|1F|1G|E|$1H|1K]]]]

Another solution similar to <a href="https://stackoverflow.com/a/1120224/1749822">Loki Astari's answer</a>, in C++11. Rows here are <code>std::tuple</code>s of a given type. The code scans one line, then scans until each delimiter, and then converts and dumps the value directly into the tuple (with a bit of template code).

<pre><code>for (auto row : csv&lt;std::string, int, float&gt;(file, ',')) {
 std::cout &lt;&lt; "first col: " &lt;&lt; std::get&lt;0&gt;(row) &lt;&lt; std::endl;
}
</code></pre>

Advanges:

<ul>
<li>quite clean and simple to use, only C++11.</li>
<li>automatic type conversion into <code>std::tuple&lt;t1, ...&gt;</code> via <code>operator&gt;&gt;</code>.</li>
</ul>

What's missing:

<ul>
<li>escaping and quoting</li>
<li>no error handling in case of malformed CSV.</li>
</ul>

The main code:

<pre><code>#include &lt;iterator&gt;
#include &lt;sstream&gt;
#include &lt;string&gt;

namespace csvtools {
 /// Read the last element of the tuple without calling recursively
 template &lt;std::size_t idx, class... fields&gt;
 typename std::enable_if&lt;idx &gt;= std::tuple_size&lt;std::tuple&lt;fields...&gt;&gt;::value - 1&gt;::type
 read_tuple(std::istream &amp;in, std::tuple&lt;fields...&gt; &amp;out, const char delimiter) {
 std::string cell;
 std::getline(in, cell, delimiter);
 std::stringstream cell_stream(cell);
 cell_stream &gt;&gt; std::get&lt;idx&gt;(out);
 }

 /// Read the @p idx-th element of the tuple and then calls itself with @p idx + 1 to
 /// read the next element of the tuple. Automatically falls in the previous case when
 /// reaches the last element of the tuple thanks to enable_if
 template &lt;std::size_t idx, class... fields&gt;
 typename std::enable_if&lt;idx &lt; std::tuple_size&lt;std::tuple&lt;fields...&gt;&gt;::value - 1&gt;::type
 read_tuple(std::istream &amp;in, std::tuple&lt;fields...&gt; &amp;out, const char delimiter) {
 std::string cell;
 std::getline(in, cell, delimiter);
 std::stringstream cell_stream(cell);
 cell_stream &gt;&gt; std::get&lt;idx&gt;(out);
 read_tuple&lt;idx + 1, fields...&gt;(in, out, delimiter);
 }
}

/// Iterable csv wrapper around a stream. @p fields the list of types that form up a row.
template &lt;class... fields&gt;
class csv {
 std::istream &amp;_in;
 const char _delim;
public:
 typedef std::tuple&lt;fields...&gt; value_type;
 class iterator;

 /// Construct from a stream.
 inline csv(std::istream &amp;in, const char delim) : _in(in), _delim(delim) {}

 /// Status of the underlying stream
 /// @{
 inline bool good() const {
 return _in.good();
 }
 inline const std::istream &amp;underlying_stream() const {
 return _in;
 }
 /// @}

 inline iterator begin();
 inline iterator end();
private:

 /// Reads a line into a stringstream, and then reads the line into a tuple, that is returned
 inline value_type read_row() {
 std::string line;
 std::getline(_in, line);
 std::stringstream line_stream(line);
 std::tuple&lt;fields...&gt; retval;
 csvtools::read_tuple&lt;0, fields...&gt;(line_stream, retval, _delim);
 return retval;
 }
};

/// Iterator; just calls recursively @ref csv::read_row and stores the result.
template &lt;class... fields&gt;
class csv&lt;fields...&gt;::iterator {
 csv::value_type _row;
 csv *_parent;
public:
 typedef std::input_iterator_tag iterator_category;
 typedef csv::value_type value_type;
 typedef std::size_t difference_type;
 typedef csv::value_type * pointer;
 typedef csv::value_type &amp; reference;

 /// Construct an empty/end iterator
 inline iterator() : _parent(nullptr) {}
 /// Construct an iterator at the beginning of the @p parent csv object.
 inline iterator(csv &amp;parent) : _parent(parent.good() ? &amp;parent : nullptr) {
 ++(*this);
 }

 /// Read one row, if possible. Set to end if parent is not good anymore.
 inline iterator &amp;operator++() {
 if (_parent != nullptr) {
 _row = _parent-&gt;read_row();
 if (!_parent-&gt;good()) {
 _parent = nullptr;
 }
 }
 return *this;
 }

 inline iterator operator++(int) {
 iterator copy = *this;
 ++(*this);
 return copy;
 }

 inline csv::value_type const &amp;operator*() const {
 return _row;
 }

 inline csv::value_type const *operator-&gt;() const {
 return &amp;_row;
 }

 bool operator==(iterator const &amp;other) {
 return (this == &amp;other) or (_parent == nullptr and other._parent == nullptr);
 }
 bool operator!=(iterator const &amp;other) {
 return not (*this == other);
 }
};

template &lt;class... fields&gt;
typename csv&lt;fields...&gt;::iterator csv&lt;fields...&gt;::begin() {
 return iterator(*this);
}

template &lt;class... fields&gt;
typename csv&lt;fields...&gt;::iterator csv&lt;fields...&gt;::end() {
 return iterator();
}
</code></pre>

I put a tiny working example on <a href="https://github.com/LizardM4/ballin-octo-tribble/tree/master/csv" rel="nofollow noreferrer">GitHub</a>; I've been using it for parsing some numerical data and it served its purpose.

blocks|key|4322180|text|因为我现在还不习惯boost，所以我会建议一个更简单的解决方案。假设您的.csv文件有100行，每行有10个数字，用'，‘分隔。您可以使用以下代码以数组的形式加载此数据：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4322181|#include+<iostream>
#include+<fstream>
#include+<sstream>
#include+<string>
using+namespace+std;

int+main()
{
++++int+A[100][10];
++++ifstream+ifs;
++++ifs.open("name_of_file.csv");
++++string+s1;
++++char+c;
++++for(int+k=0;+k<100;+k%2B%2B)
++++{
++++++++getline(ifs,s1);
++++++++stringstream+stream(s1);
++++++++int+j=0;
++++++++while(1)
++++++++{
++++++++++++stream+>>A[k][j];
++++++++++++stream+>>+c;
++++++++++++j%2B%2B;
++++++++++++if(!stream)+{break;}
++++++++}
++++}


}|code-block|syntax|javascript|4322182|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Since i'm not used to boost right now, I will suggest a more simple solution. Lets suppose that your .csv file has 100 lines with 10 numbers in each line separated by a ','. You could load this data in the form of an array with the following code:

<pre><code>#include &lt;iostream&gt;
#include &lt;fstream&gt;
#include &lt;sstream&gt;
#include &lt;string&gt;
using namespace std;

int main()
{
 int A[100][10];
 ifstream ifs;
 ifs.open("name_of_file.csv");
 string s1;
 char c;
 for(int k=0; k&lt;100; k++)
 {
 getline(ifs,s1);
 stringstream stream(s1);
 int j=0;
 while(1)
 {
 stream &gt;&gt;A[k][j];
 stream &gt;&gt; c;
 j++;
 if(!stream) {break;}
 }
 }


}
</code></pre>

blocks|key|1417501|text|我需要一个易于使用的C%2B%2B库来解析CSV文件，但是找不到任何可用的库，所以我最终构建了一个。Rapidcsv是一个仅限C%2B%2B11头的库，它允许以选择的数据类型直接访问已解析的列(或行)作为向量。例如：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1417502|#include+<iostream>
#include+<vector>
#include+<rapidcsv.h>

int+main()
{
++rapidcsv::Document+doc("../tests/msft.csv");

++std::vector<float>+close+=+doc.GetColumn<float>("Close");
++std::cout+<<+"Read+"+<<+close.size()+<<+"+values."+<<+std::endl;
}|code-block|syntax|javascript|1417503|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/d99kris/rapidcsv/^0|1A|8|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

I needed an easy-to-use C++ library for parsing CSV files but couldn't find any available, so I ended up building one.
<a href="https://github.com/d99kris/rapidcsv/" rel="nofollow noreferrer">Rapidcsv</a> is a C++11 header-only library which gives direct access to parsed columns (or rows) as vectors, in datatype of choice. For example:

<pre><code>#include &lt;iostream&gt;
#include &lt;vector&gt;
#include &lt;rapidcsv.h&gt;

int main()
{
 rapidcsv::Document doc("../tests/msft.csv");

 std::vector&lt;float&gt; close = doc.GetColumn&lt;float&gt;("Close");
 std::cout &lt;&lt; "Read " &lt;&lt; close.size() &lt;&lt; " values." &lt;&lt; std::endl;
}
</code></pre>

blocks|key|4322260|text|I+wrote+a+header-only,+C%2B%2B11+CSV+parser。它经过了良好的测试，速度很快，支持整个CSV规范(引号字段、引号中的分隔符/终止符、引号转义等)，并且可以配置为考虑到不符合规范的CSV。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|4322261|配置是通过流畅的界面完成的：|4322262|//+constructor+accepts+any+input+stream
CsvParser+parser+=+CsvParser(std::cin)
++.delimiter(';')++++//+delimited+by+;+instead+of+,
++.quote('\'')+++++++//+quoted+fields+use+'+instead+of+"
++.terminator('\0');+//+terminated+by+\0+instead+of+by+\r\n,+\n,+or+\r|code-block|syntax|javascript|4322263|解析只是一个基于for循环的范围：|4322264|#include+<iostream>
#include+"../parser.hpp"

using+namespace+aria::csv;

int+main()+{
++std::ifstream+f("some_file.csv");
++CsvParser+parser(f);

++for+(auto&+row+:+parser)+{
++++for+(auto&+field+:+row)+{
++++++std::cout+<<+field+<<+"+%7C+";
++++}
++++std::cout+<<+std::endl;
++}
}|4322265|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/AriaFallah/csv-parser^0|0|13|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|6|7|10|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|11|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|9|@]|C|$]]|$1|M|3|N|5|H|7|13|8|@]|9|@]|C|$I|J]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]]]

<a href="https://github.com/AriaFallah/csv-parser" rel="noreferrer">I wrote a header-only, C++11 CSV parser</a>. It's well tested, fast, supports the entire CSV spec (quoted fields, delimiter/terminator in quotes, quote escaping, etc.), and is configurable to account for the CSVs that don't adhere to the specification.

Configuration is done through a fluent interface:

<pre><code>// constructor accepts any input stream
CsvParser parser = CsvParser(std::cin)
 .delimiter(';') // delimited by ; instead of ,
 .quote('\'') // quoted fields use ' instead of "
 .terminator('\0'); // terminated by \0 instead of by \r\n, \n, or \r
</code></pre>

Parsing is just a range based for loop:

<pre><code>#include &lt;iostream&gt;
#include "../parser.hpp"

using namespace aria::csv;

int main() {
 std::ifstream f("some_file.csv");
 CsvParser parser(f);

 for (auto&amp; row : parser) {
 for (auto&amp; field : row) {
 std::cout &lt;&lt; field &lt;&lt; " | ";
 }
 std::cout &lt;&lt; std::endl;
 }
}
</code></pre>

blocks|key|1105592|text|您可以使用这个库：https://github.com/vadamsky/csvworker|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1105593|代码示例：|1105594|#include+<iostream>
#include+"csvworker.h"

using+namespace+std;

int+main()
{
++++//
++++CsvWorker+csv;
++++csv.loadFromFile("example.csv");
++++cout+<<+csv.getRowsNumber()+<<+"++"+<<+csv.getColumnsNumber()+<<+endl;

++++csv.getFieldRef(0,+2)+=+"0";
++++csv.getFieldRef(1,+1)+=+"0";
++++csv.getFieldRef(1,+3)+=+"0";
++++csv.getFieldRef(2,+0)+=+"0";
++++csv.getFieldRef(2,+4)+=+"0";
++++csv.getFieldRef(3,+1)+=+"0";
++++csv.getFieldRef(3,+3)+=+"0";
++++csv.getFieldRef(4,+2)+=+"0";

++++for(unsigned+int+i=0;i<csv.getRowsNumber();%2B%2Bi)
++++{
++++++++//cout+<<+csv.getRow(i)+<<+endl;
++++++++for(unsigned+int+j=0;j<csv.getColumnsNumber();%2B%2Bj)
++++++++{
++++++++++++cout+<<+csv.getField(i,+j)+<<+".";
++++++++}
++++++++cout+<<+endl;
++++}

++++csv.saveToFile("test.csv");

++++//
++++CsvWorker+csv2(4,4);

++++csv2.getFieldRef(0,+0)+=+"a";
++++csv2.getFieldRef(0,+1)+=+"b";
++++csv2.getFieldRef(0,+2)+=+"r";
++++csv2.getFieldRef(0,+3)+=+"a";
++++csv2.getFieldRef(1,+0)+=+"c";
++++csv2.getFieldRef(1,+1)+=+"a";
++++csv2.getFieldRef(1,+2)+=+"d";
++++csv2.getFieldRef(2,+0)+=+"a";
++++csv2.getFieldRef(2,+1)+=+"b";
++++csv2.getFieldRef(2,+2)+=+"r";
++++csv2.getFieldRef(2,+3)+=+"a";

++++csv2.saveToFile("test2.csv");

++++return+0;
}|code-block|syntax|javascript|1105595|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/vadamsky/csvworker^0|9|11|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|C|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

You can use this library:
<a href="https://github.com/vadamsky/csvworker" rel="nofollow noreferrer">https://github.com/vadamsky/csvworker</a>

Code for example:

<pre><code>#include &lt;iostream&gt;
#include "csvworker.h"

using namespace std;

int main()
{
 //
 CsvWorker csv;
 csv.loadFromFile("example.csv");
 cout &lt;&lt; csv.getRowsNumber() &lt;&lt; " " &lt;&lt; csv.getColumnsNumber() &lt;&lt; endl;

 csv.getFieldRef(0, 2) = "0";
 csv.getFieldRef(1, 1) = "0";
 csv.getFieldRef(1, 3) = "0";
 csv.getFieldRef(2, 0) = "0";
 csv.getFieldRef(2, 4) = "0";
 csv.getFieldRef(3, 1) = "0";
 csv.getFieldRef(3, 3) = "0";
 csv.getFieldRef(4, 2) = "0";

 for(unsigned int i=0;i&lt;csv.getRowsNumber();++i)
 {
 //cout &lt;&lt; csv.getRow(i) &lt;&lt; endl;
 for(unsigned int j=0;j&lt;csv.getColumnsNumber();++j)
 {
 cout &lt;&lt; csv.getField(i, j) &lt;&lt; ".";
 }
 cout &lt;&lt; endl;
 }

 csv.saveToFile("test.csv");

 //
 CsvWorker csv2(4,4);

 csv2.getFieldRef(0, 0) = "a";
 csv2.getFieldRef(0, 1) = "b";
 csv2.getFieldRef(0, 2) = "r";
 csv2.getFieldRef(0, 3) = "a";
 csv2.getFieldRef(1, 0) = "c";
 csv2.getFieldRef(1, 1) = "a";
 csv2.getFieldRef(1, 2) = "d";
 csv2.getFieldRef(2, 0) = "a";
 csv2.getFieldRef(2, 1) = "b";
 csv2.getFieldRef(2, 2) = "r";
 csv2.getFieldRef(2, 3) = "a";

 csv2.saveToFile("test2.csv");

 return 0;
}
</code></pre>

blocks|key|4322333|text|当你使用像boost::spirit这样漂亮的东西时，你一定会感到骄傲|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4322334|在这里，我尝试在这个链接CSV+specs上创建一个(几乎)符合CSV规范的解析器(我在字段中不需要换行符。此外，逗号周围的空格也会被删除)。|4322335|在您克服了等待10秒来编译此代码的令人震惊的体验之后:)，您可以坐下来享受这段代码。|4322336|//+csvparser.cpp
#include+<boost/spirit/include/qi.hpp>
#include+<boost/spirit/include/phoenix_operator.hpp>

#include+<iostream>
#include+<string>

namespace+qi+=+boost::spirit::qi;
namespace+bascii+=+boost::spirit::ascii;

template+<typename+Iterator>
struct+csv_parser+:+qi::grammar<Iterator,+std::vector<std::string>(),+
++++bascii::space_type>
{
++++qi::rule<Iterator,+char()+++++++++++++++++++++++++++++++++++++++++++>+COMMA;
++++qi::rule<Iterator,+char()+++++++++++++++++++++++++++++++++++++++++++>+DDQUOTE;
++++qi::rule<Iterator,+std::string(),+++++++++++++++bascii::space_type++>+non_escaped;
++++qi::rule<Iterator,+std::string(),+++++++++++++++bascii::space_type++>+escaped;
++++qi::rule<Iterator,+std::string(),+++++++++++++++bascii::space_type++>+field;
++++qi::rule<Iterator,+std::vector<std::string>(),++bascii::space_type++>+start;

++++csv_parser()+:+csv_parser::base_type(start)
++++{
++++++++using+namespace+qi;
++++++++using+qi::lit;
++++++++using+qi::lexeme;
++++++++using+bascii::char_;

++++++++start+++++++=+field+%25+',';
++++++++field+++++++=+escaped+%7C+non_escaped;
++++++++escaped+++++=+lexeme['"'+>>+*(+char_+-(char_('"')+%7C+',')+%7C+COMMA+%7C+DDQUOTE)++>>+'"'];
++++++++non_escaped+=+lexeme[+++++++*(+char_+-(char_('"')+%7C+',')++++++++++++++++++)++++++++];
++++++++DDQUOTE+++++=+lit("\"\"")+++++++[_val+=+'"'];
++++++++COMMA+++++++=+lit(",")++++++++++[_val+=+','];
++++}

};

int+main()
{
++++std::cout+<<+"Enter+CSV+lines+[empty]+to+quit\n";

++++using+bascii::space;
++++typedef+std::string::const_iterator+iterator_type;
++++typedef+csv_parser<iterator_type>+csv_parser;

++++csv_parser+grammar;
++++std::string+str;
++++int+fid;
++++while+(getline(std::cin,+str))
++++{
++++++++fid+=+0;

++++++++if+(str.empty())
++++++++++++break;

++++++++std::vector<std::string>+csv;
++++++++std::string::const_iterator+it_beg+=+str.begin();
++++++++std::string::const_iterator+it_end+=+str.end();
++++++++bool+r+=+phrase_parse(it_beg,+it_end,+grammar,+space,+csv);

++++++++if+(r+&&+it_beg+==+it_end)
++++++++{
++++++++++++std::cout+<<+"Parsing+succeeded\n";
++++++++++++for+(auto&+field:+csv)
++++++++++++{
++++++++++++++++std::cout+<<+"field+"+<<+%2B%2Bfid+<<+":+"+<<+field+<<+std::endl;
++++++++++++}
++++++++}
++++++++else
++++++++{
++++++++++++std::cout+<<+"Parsing+failed\n";
++++++++}
++++}

++++return+0;
}|code-block|syntax|javascript|4322337|编译：|4322338|make+csvparser|4322339|测试(从Wikipedia窃取的示例)：|4322340|./csvparser
Enter+CSV+lines+[empty]+to+quit

1999,Chevy,"Venture+""Extended+Edition,+Very+Large""",,5000.00
Parsing+succeeded
field+1:+1999
field+2:+Chevy
field+3:+Venture+"Extended+Edition,+Very+Large"
field+4:+
field+5:+5000.00

1999,Chevy,"Venture+""Extended+Edition,+Very+Large""",,5000.00"
Parsing+failed|4322341|entityMap|0|LINK|mutability|MUTABLE|url|http://www.ietf.org/rfc/rfc4180.txt|1|https://en.wikipedia.org/wiki/Comma-separated_values#Example^0|5|D|0|C|9|0|0|0|0|0|0|4|9|1|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|19|8|@]|D|@$9|1A|A|1B|1|1C]]|E|$]]|$1|H|3|I|5|6|7|1D|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|1E|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1F|8|@]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1G|8|@]|D|@]|E|$M|N]]|$1|S|3|T|5|6|7|1H|8|@]|D|@$9|1I|A|1J|1|1K]]|E|$]]|$1|U|3|V|5|L|7|1L|8|@]|D|@]|E|$M|N]]|$1|W|3|-4|5|6|7|1M|8|@]|D|@]|E|$]]]|X|$Y|$5|Z|10|11|E|$12|13]]|14|$5|Z|10|11|E|$12|15]]]]

You gotta feel proud when you use something so beautiful as <code>boost::spirit</code>

Here my attempt of a parser (almost) complying with the CSV specifications on this link <a href="http://www.ietf.org/rfc/rfc4180.txt" rel="nofollow noreferrer">CSV specs</a> (I didn't need line breaks within fields. Also the spaces around the commas are dismissed).

After you overcome the shocking experience of waiting 10 seconds for compiling this code :), you can sit back and enjoy.

<pre><code>// csvparser.cpp
#include &lt;boost/spirit/include/qi.hpp&gt;
#include &lt;boost/spirit/include/phoenix_operator.hpp&gt;

#include &lt;iostream&gt;
#include &lt;string&gt;

namespace qi = boost::spirit::qi;
namespace bascii = boost::spirit::ascii;

template &lt;typename Iterator&gt;
struct csv_parser : qi::grammar&lt;Iterator, std::vector&lt;std::string&gt;(), 
 bascii::space_type&gt;
{
 qi::rule&lt;Iterator, char() &gt; COMMA;
 qi::rule&lt;Iterator, char() &gt; DDQUOTE;
 qi::rule&lt;Iterator, std::string(), bascii::space_type &gt; non_escaped;
 qi::rule&lt;Iterator, std::string(), bascii::space_type &gt; escaped;
 qi::rule&lt;Iterator, std::string(), bascii::space_type &gt; field;
 qi::rule&lt;Iterator, std::vector&lt;std::string&gt;(), bascii::space_type &gt; start;

 csv_parser() : csv_parser::base_type(start)
 {
 using namespace qi;
 using qi::lit;
 using qi::lexeme;
 using bascii::char_;

 start = field % ',';
 field = escaped | non_escaped;
 escaped = lexeme['"' &gt;&gt; *( char_ -(char_('"') | ',') | COMMA | DDQUOTE) &gt;&gt; '"'];
 non_escaped = lexeme[ *( char_ -(char_('"') | ',') ) ];
 DDQUOTE = lit("\"\"") [_val = '"'];
 COMMA = lit(",") [_val = ','];
 }

};

int main()
{
 std::cout &lt;&lt; "Enter CSV lines [empty] to quit\n";

 using bascii::space;
 typedef std::string::const_iterator iterator_type;
 typedef csv_parser&lt;iterator_type&gt; csv_parser;

 csv_parser grammar;
 std::string str;
 int fid;
 while (getline(std::cin, str))
 {
 fid = 0;

 if (str.empty())
 break;

 std::vector&lt;std::string&gt; csv;
 std::string::const_iterator it_beg = str.begin();
 std::string::const_iterator it_end = str.end();
 bool r = phrase_parse(it_beg, it_end, grammar, space, csv);

 if (r &amp;&amp; it_beg == it_end)
 {
 std::cout &lt;&lt; "Parsing succeeded\n";
 for (auto&amp; field: csv)
 {
 std::cout &lt;&lt; "field " &lt;&lt; ++fid &lt;&lt; ": " &lt;&lt; field &lt;&lt; std::endl;
 }
 }
 else
 {
 std::cout &lt;&lt; "Parsing failed\n";
 }
 }

 return 0;
}
</code></pre>

Compile:

<pre><code>make csvparser
</code></pre>

Test (example stolen from <a href="https://en.wikipedia.org/wiki/Comma-separated_values#Example" rel="nofollow noreferrer">Wikipedia</a>):

<pre class="lang-none prettyprint-override"><code>./csvparser
Enter CSV lines [empty] to quit

1999,Chevy,"Venture ""Extended Edition, Very Large""",,5000.00
Parsing succeeded
field 1: 1999
field 2: Chevy
field 3: Venture "Extended Edition, Very Large"
field 4: 
field 5: 5000.00

1999,Chevy,"Venture ""Extended Edition, Very Large""",,5000.00"
Parsing failed
</code></pre>

blocks|key|116271|text|此解决方案检测到以下4种情况|type|unstyled|depth|inlineStyleRanges|entityRanges|data|116272|完整的课程在|116273|https://github.com/pedro-vicente/csv-parser|offset|length|116274|1,field+2,field+3,
1,field+2,"field+3+quoted,+with+separator",
1,field+2,"field+3
with+newline",
1,field+2,"field+3
with+newline+and+separator,",|code-block|syntax|javascript|116275|它逐个字符地读取文件，并且一次读取一行向量(字符串)，因此适用于非常大的文件。|116276|用法是|116277|迭代直到返回空行(文件末尾)。行是一个向量，其中每个条目都是一个CSV列。|116278|read_csv_t+csv;
csv.open("../test.csv");
std::vector<std::string>+row;
while+(true)
{
++row+=+csv.read_row();
++if+(row.size()+==+0)
++{
++++break;
++}
}|116279|类声明|116280|class+read_csv_t
{
public:
++read_csv_t();
++int+open(const+std::string+&file_name);
++std::vector<std::string>+read_row();
private:
++std::ifstream+m_ifs;
};|116281|实现|116282|std::vector<std::string>+read_csv_t::read_row()
{
++bool+quote_mode+=+false;
++std::vector<std::string>+row;
++std::string+column;
++char+c;
++while+(m_ifs.get(c))
++{
++++switch+(c)
++++{
++++++/////////////////////////////////////////////////////////////////////////////////////////////////////
++++++//separator+','+detected.+
++++++//in+quote+mode+add+character+to+column
++++++//push+column+if+not+in+quote+mode
++++++/////////////////////////////////////////////////////////////////////////////////////////////////////

++++case+',':
++++++if+(quote_mode+==+true)
++++++{
++++++++column+%2B=+c;
++++++}
++++++else
++++++{
++++++++row.push_back(column);
++++++++column.clear();
++++++}
++++++break;

++++++/////////////////////////////////////////////////////////////////////////////////////////////////////
++++++//quote+'"'+detected.+
++++++//toggle+quote+mode
++++++/////////////////////////////////////////////////////////////////////////////////////////////////////

++++case+'"':
++++++quote_mode+=+!quote_mode;
++++++break;

++++++/////////////////////////////////////////////////////////////////////////////////////////////////////
++++++//line+end+detected
++++++//in+quote+mode+add+character+to+column
++++++//return+row+if+not+in+quote+mode
++++++/////////////////////////////////////////////////////////////////////////////////////////////////////

++++case+'\n':
++++case+'\r':
++++++if+(quote_mode+==+true)
++++++{
++++++++column+%2B=+c;
++++++}
++++++else
++++++{
++++++++return+row;
++++++}
++++++break;

++++++/////////////////////////////////////////////////////////////////////////////////////////////////////
++++++//default,+add+character+to+column
++++++/////////////////////////////////////////////////////////////////////////////////////////////////////

++++default:
++++++column+%2B=+c;
++++++break;
++++}
++}

++//return+empty+vector+if+end+of+file+detected+
++m_ifs.close();
++std::vector<std::string>+v;
++return+v;
}|116283|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|17|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|19|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1A|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1B|8|@]|9|@$F|1C|G|1D|1|1E]]|A|$]]|$1|H|3|I|5|J|7|1F|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1G|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|1H|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1I|8|@]|9|@]|A|$]]|$1|S|3|T|5|J|7|1J|8|@]|9|@]|A|$K|L]]|$1|U|3|V|5|6|7|1K|8|@]|9|@]|A|$]]|$1|W|3|X|5|J|7|1L|8|@]|9|@]|A|$K|L]]|$1|Y|3|Z|5|6|7|1M|8|@]|9|@]|A|$]]|$1|10|3|11|5|J|7|1N|8|@]|9|@]|A|$K|L]]|$1|12|3|-4|5|6|7|1O|8|@]|9|@]|A|$]]]|13|$14|$5|15|16|17|A|$18|E]]]]

This solution detects these 4 cases

complete class is at

<a href="https://github.com/pedro-vicente/csv-parser" rel="nofollow noreferrer">https://github.com/pedro-vicente/csv-parser</a>

<pre><code>1,field 2,field 3,
1,field 2,"field 3 quoted, with separator",
1,field 2,"field 3
with newline",
1,field 2,"field 3
with newline and separator,",
</code></pre>

It reads the file character by character, and reads 1 row at a time to a vector (of strings), therefore suitable for very large files.

Usage is

Iterate until an empty row is returned (end of file). A row is a vector where each entry is a CSV column.

<pre><code>read_csv_t csv;
csv.open("../test.csv");
std::vector&lt;std::string&gt; row;
while (true)
{
 row = csv.read_row();
 if (row.size() == 0)
 {
 break;
 }
}
</code></pre>

the class declaration

<pre><code>class read_csv_t
{
public:
 read_csv_t();
 int open(const std::string &amp;file_name);
 std::vector&lt;std::string&gt; read_row();
private:
 std::ifstream m_ifs;
};
</code></pre>

the implementation

<pre><code>std::vector&lt;std::string&gt; read_csv_t::read_row()
{
 bool quote_mode = false;
 std::vector&lt;std::string&gt; row;
 std::string column;
 char c;
 while (m_ifs.get(c))
 {
 switch (c)
 {
 /////////////////////////////////////////////////////////////////////////////////////////////////////
 //separator ',' detected. 
 //in quote mode add character to column
 //push column if not in quote mode
 /////////////////////////////////////////////////////////////////////////////////////////////////////

 case ',':
 if (quote_mode == true)
 {
 column += c;
 }
 else
 {
 row.push_back(column);
 column.clear();
 }
 break;

 /////////////////////////////////////////////////////////////////////////////////////////////////////
 //quote '"' detected. 
 //toggle quote mode
 /////////////////////////////////////////////////////////////////////////////////////////////////////

 case '"':
 quote_mode = !quote_mode;
 break;

 /////////////////////////////////////////////////////////////////////////////////////////////////////
 //line end detected
 //in quote mode add character to column
 //return row if not in quote mode
 /////////////////////////////////////////////////////////////////////////////////////////////////////

 case '\n':
 case '\r':
 if (quote_mode == true)
 {
 column += c;
 }
 else
 {
 return row;
 }
 break;

 /////////////////////////////////////////////////////////////////////////////////////////////////////
 //default, add character to column
 /////////////////////////////////////////////////////////////////////////////////////////////////////

 default:
 column += c;
 break;
 }
 }

 //return empty vector if end of file detected 
 m_ifs.close();
 std::vector&lt;std::string&gt; v;
 return v;
}
</code></pre>

blocks|key|116297|text|如果您使用的是Visual+Studio+/+MFC，下面的解决方案可能会让您的工作更轻松。它同时支持Unicode和MBCS，有注释，除了CString之外没有其他依赖项，对我来说已经足够好了。它不支持嵌入在带引号的字符串中的换行符，但我不在乎，只要它在这种情况下不崩溃，它就不会崩溃。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|116298|总体策略是，将引号和空字符串作为特例处理，其余的使用Tokenize。对于带引号的字符串，策略是，找到真正的闭合引号，跟踪是否遇到连续的引号对。如果是，请使用Replace将对转换为单对。毫无疑问，还有更有效的方法，但在我的情况下，性能还不够关键，不足以证明进一步的优化是合理的。|116299|class+CParseCSV+{
public:
//+Construction
++++CParseCSV(const+CString&+sLine);

//+Attributes
++++bool++++GetString(CString&+sDest);

protected:
++++CString+m_sLine;++++//+line+to+extract+tokens+from
++++int+++++m_nLen;+++++//+line+length+in+characters
++++int+++++m_iPos;+++++//+index+of+current+position
};

CParseCSV::CParseCSV(const+CString&+sLine)+:+m_sLine(sLine)
{
++++m_nLen+=+m_sLine.GetLength();
++++m_iPos+=+0;
}

bool+CParseCSV::GetString(CString&+sDest)
{
++++if+(m_iPos+<+0+%7C%7C+m_iPos+>+m_nLen)++//+if+position+out+of+range
++++++++return+false;
++++if+(m_iPos+==+m_nLen)+{+//+if+at+end+of+string
++++++++sDest.Empty();++//+return+empty+token
++++++++m_iPos+=+-1;++++//+really+done+now
++++++++return+true;
++++}
++++if+(m_sLine[m_iPos]+==+'\"')+{++//+if+current+char+is+double+quote
++++++++m_iPos%2B%2B;+++//+advance+to+next+char
++++++++int+iTokenStart+=+m_iPos;
++++++++bool++++bHasEmbeddedQuotes+=+false;
++++++++while+(m_iPos+<+m_nLen)+{+++//+while+more+chars+to+parse
++++++++++++if+(m_sLine[m_iPos]+==+'\"')+{++//+if+current+char+is+double+quote
++++++++++++++++//+if+next+char+exists+and+is+also+double+quote
++++++++++++++++if+(m_iPos+<+m_nLen+-+1+&&+m_sLine[m_iPos+%2B+1]+==+'\"')+{
++++++++++++++++++++//+found+pair+of+consecutive+double+quotes
++++++++++++++++++++bHasEmbeddedQuotes+=+true;++//+request+conversion
++++++++++++++++++++m_iPos%2B%2B;+++//+skip+first+quote+in+pair
++++++++++++++++}+else++//+next+char+doesn't+exist+or+is+normal
++++++++++++++++++++break;++//+found+closing+quote;+exit+loop
++++++++++++}
++++++++++++m_iPos%2B%2B;+++//+advance+to+next+char
++++++++}
++++++++sDest+=+m_sLine.Mid(iTokenStart,+m_iPos+-+iTokenStart);
++++++++if+(bHasEmbeddedQuotes)+//+if+string+contains+embedded+quote+pairs
++++++++++++sDest.Replace(_T("\"\""),+_T("\""));++++//+convert+pairs+to+singles
++++++++m_iPos+%2B=+2;++++//+skip+closing+quote+and+trailing+delimiter+if+any
++++}+else+if+(m_sLine[m_iPos]+==+',')+{++++//+else+if+char+is+comma
++++++++sDest.Empty();++//+return+empty+token
++++++++m_iPos%2B%2B;+++//+advance+to+next+char
++++}+else+{++++//+else+get+next+comma-delimited+token
++++++++sDest+=+m_sLine.Tokenize(_T(","),+m_iPos);
++++}
++++return+true;
}

//+calling+code+should+look+something+like+this:

++++CStdioFile++fIn(pszPath,+CFile::modeRead);
++++CString+sLine,+sToken;
++++while+(fIn.ReadString(sLine))+{+//+for+each+line+of+input+file
++++++++if+(!sLine.IsEmpty())+{+//+ignore+blank+lines
++++++++++++CParseCSV+++csv(sLine);
++++++++++++while+(csv.GetString(sToken))+{
++++++++++++++++//+do+something+with+sToken+here
++++++++++++}
++++++++}
++++}|code-block|syntax|javascript|116300|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

If you're using Visual Studio / MFC, the following solution may make your life easier. It supports both Unicode and MBCS, has comments, doesn't have dependencies other than CString, and works well enough for me. It doesn't support line breaks embedded within a quoted string, but I don't care so long as it doesn't crash in that case, which it doesn't.

The overall strategy is, handle quoted and empty strings as special cases, and use Tokenize for the rest. For quoted strings, the strategy is, find the real closing quote, keeping track of whether pairs of consecutive quotes were encountered. If they were, use Replace to convert the pairs to singles. No doubt there are more efficient methods but performance wasn't sufficiently critical in my case to justify further optimization.

<pre><code>class CParseCSV {
public:
// Construction
 CParseCSV(const CString&amp; sLine);

// Attributes
 bool GetString(CString&amp; sDest);

protected:
 CString m_sLine; // line to extract tokens from
 int m_nLen; // line length in characters
 int m_iPos; // index of current position
};

CParseCSV::CParseCSV(const CString&amp; sLine) : m_sLine(sLine)
{
 m_nLen = m_sLine.GetLength();
 m_iPos = 0;
}

bool CParseCSV::GetString(CString&amp; sDest)
{
 if (m_iPos &lt; 0 || m_iPos &gt; m_nLen) // if position out of range
 return false;
 if (m_iPos == m_nLen) { // if at end of string
 sDest.Empty(); // return empty token
 m_iPos = -1; // really done now
 return true;
 }
 if (m_sLine[m_iPos] == '\"') { // if current char is double quote
 m_iPos++; // advance to next char
 int iTokenStart = m_iPos;
 bool bHasEmbeddedQuotes = false;
 while (m_iPos &lt; m_nLen) { // while more chars to parse
 if (m_sLine[m_iPos] == '\"') { // if current char is double quote
 // if next char exists and is also double quote
 if (m_iPos &lt; m_nLen - 1 &amp;&amp; m_sLine[m_iPos + 1] == '\"') {
 // found pair of consecutive double quotes
 bHasEmbeddedQuotes = true; // request conversion
 m_iPos++; // skip first quote in pair
 } else // next char doesn't exist or is normal
 break; // found closing quote; exit loop
 }
 m_iPos++; // advance to next char
 }
 sDest = m_sLine.Mid(iTokenStart, m_iPos - iTokenStart);
 if (bHasEmbeddedQuotes) // if string contains embedded quote pairs
 sDest.Replace(_T("\"\""), _T("\"")); // convert pairs to singles
 m_iPos += 2; // skip closing quote and trailing delimiter if any
 } else if (m_sLine[m_iPos] == ',') { // else if char is comma
 sDest.Empty(); // return empty token
 m_iPos++; // advance to next char
 } else { // else get next comma-delimited token
 sDest = m_sLine.Tokenize(_T(","), m_iPos);
 }
 return true;
}

// calling code should look something like this:

 CStdioFile fIn(pszPath, CFile::modeRead);
 CString sLine, sToken;
 while (fIn.ReadString(sLine)) { // for each line of input file
 if (!sLine.IsEmpty()) { // ignore blank lines
 CParseCSV csv(sLine);
 while (csv.GetString(sToken)) {
 // do something with sToken here
 }
 }
 }
</code></pre>

blocks|key|1105731|text|我有一个更快的解决方案，最初是为了解决这个问题：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105732|How+to+pull+specific+part+of+different+strings?|offset|length|1105733|但很明显它已经关闭了。不过，我不打算把它扔掉：|1105734|#include+<iostream>
#include+<string>
#include+<regex>

std::string+text+=+"\"4,\"\"3\"\",\"\"Mon+May+11+03:17:40+UTC+2009\"\",\"\"kindle2\"\",\"\"tpryan\"\",\"\"TEXT+HERE\"\"\";;;;";

int+main()
{
++++std::regex+r("(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")");
++++std::smatch+m;
++++std::regex_search(text,+m,+r);
++++std::cout<<"FOUND:+"<<m[9]<<std::endl;

++++return+0;
}|code-block|syntax|javascript|1105735|只需通过索引从smatch集合中挑选出您想要的任何匹配。正则表达式是极乐。|1105736|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/53858950/how-to-pull-specific-part-of-different-strings^0|0|0|1B|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@$D|Y|E|Z|1|10]]|A|$]]|$1|F|3|G|5|6|7|11|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|12|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|13|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

I've got a way quicker solution, was originally intended for this question:

<a href="https://stackoverflow.com/questions/53858950/how-to-pull-specific-part-of-different-strings">How to pull specific part of different strings?</a>

But it was closed obviously. I'm not about to throw this away though:

<pre><code>#include &lt;iostream&gt;
#include &lt;string&gt;
#include &lt;regex&gt;

std::string text = "\"4,\"\"3\"\",\"\"Mon May 11 03:17:40 UTC 2009\"\",\"\"kindle2\"\",\"\"tpryan\"\",\"\"TEXT HERE\"\"\";;;;";

int main()
{
 std::regex r("(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")(\".*\")");
 std::smatch m;
 std::regex_search(text, m, r);
 std::cout&lt;&lt;"FOUND: "&lt;&lt;m[9]&lt;&lt;std::endl;

 return 0;
}
</code></pre>

Just pick out whichever match you want from the smatch collection by index.
Regex is bliss.

blocks|key|4322468|text|用流实现CSV文件行的解析|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|4322469|我写了一个解析CSV文件行的小示例，如果需要，可以使用for和while循环进行开发：|4322470|#include+<iostream>
#include+<fstream>
#include+<string.h>

using+namespace+std;

int+main()+{


ifstream+fin("Infile.csv");
ofstream+fout("OutFile.csv");
string+strline,+strremain,+strCol1+,+strout;

string+delimeter+=";";

int+d1;|code-block|syntax|javascript|4322471|要继续到文件结尾，请执行以下操作：|4322472|while+(!fin.eof()){+|4322473|从InFile获取第一行：|4322474|++++getline(fin,strline,'\n');++++++|4322475|查找行中的分隔符位置：|4322476|++++d1+=+strline.find(';');|4322477|并解析第一列：|4322478|++++strCol1+=+strline.substr(0,d1);+//+parse+first+Column
++++d1%2B%2B;
++++strremain+=+strline.substr(d1);+//+remaining+line|4322479|创建CSV格式的输出行：|4322480|++++strout.append(strCol1);
++++strout.append(delimeter);|4322481|将行写入输出文件：|4322482|++++fout+<<+strout+<<+endl;+//out+file+line

}+

fin.close();
fout.close();

return(0);
}|4322483|此代码已编译并运行。祝好运!|4322484|entityMap^0|B|2|0|0|17|0|0|0|H|0|0|0|D|0|0|0|B|0|0|0|7|0|0|0|C|0|0|0|9|0|0|0|E|0^^$0|@$1|2|3|4|5|6|7|1E|8|@$9|1F|A|1G|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1H|8|@$9|1I|A|1J|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|1K|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1L|8|@$9|1M|A|1N|B|C]]|D|@]|E|$]]|$1|O|3|P|5|J|7|1O|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1P|8|@$9|1Q|A|1R|B|C]]|D|@]|E|$]]|$1|S|3|T|5|J|7|1S|8|@]|D|@]|E|$K|L]]|$1|U|3|V|5|6|7|1T|8|@$9|1U|A|1V|B|C]]|D|@]|E|$]]|$1|W|3|X|5|J|7|1W|8|@]|D|@]|E|$K|L]]|$1|Y|3|Z|5|6|7|1X|8|@$9|1Y|A|1Z|B|C]]|D|@]|E|$]]|$1|10|3|11|5|J|7|20|8|@]|D|@]|E|$K|L]]|$1|12|3|13|5|6|7|21|8|@$9|22|A|23|B|C]]|D|@]|E|$]]|$1|14|3|15|5|J|7|24|8|@]|D|@]|E|$K|L]]|$1|16|3|17|5|6|7|25|8|@$9|26|A|27|B|C]]|D|@]|E|$]]|$1|18|3|19|5|J|7|28|8|@]|D|@]|E|$K|L]]|$1|1A|3|1B|5|6|7|29|8|@$9|2A|A|2B|B|C]]|D|@]|E|$]]|$1|1C|3|-4|5|6|7|2C|8|@]|D|@]|E|$]]]|1D|$]]

Parsing CSV file lines with Stream

I wrote a small example of parsing CSV file lines, it can be developed with for and while loops if desired:

<pre><code>#include &lt;iostream&gt;
#include &lt;fstream&gt;
#include &lt;string.h&gt;

using namespace std;

int main() {


ifstream fin("Infile.csv");
ofstream fout("OutFile.csv");
string strline, strremain, strCol1 , strout;

string delimeter =";";

int d1;
</code></pre>

to continue until the end of the file:

<pre><code>while (!fin.eof()){ 
</code></pre>

get first line from InFile :

<pre><code> getline(fin,strline,'\n'); 
</code></pre>

find delimeter position in line:

<pre><code> d1 = strline.find(';');
</code></pre>

and parse first column:

<pre><code> strCol1 = strline.substr(0,d1); // parse first Column
 d1++;
 strremain = strline.substr(d1); // remaining line
</code></pre>

create output line in CSV format:

<pre><code> strout.append(strCol1);
 strout.append(delimeter);
</code></pre>

write line to Out File:

<pre><code> fout &lt;&lt; strout &lt;&lt; endl; //out file line

} 

fin.close();
fout.close();

return(0);
}
</code></pre>

This code is compiled and running. Good luck!

blocks|key|4322543|text|就像每个人都提出自己的解决方案一样，这是我使用模板、lambda和tuple的解决方案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4322544|它可以将任何包含所需列的CSV转换为元组的C%2B%2B向量。|4322545|它的工作方式是在元组中定义每个CSV线元素类型。|4322546|您还需要为每个元素定义std::string到type的转换Formatter+lambda+(例如，使用std::atod+)。|offset|length|style|CODE|4322547|然后，您将获得与CSV数据相对应的该结构的向量。|4322548|您可以很容易地重用它来匹配任何CSV结构。|4322549|StringsHelpers.hpp|BOLD|4322550|#include+<string>
#include+<fstream>
#include+<vector>
#include+<functional>

namespace+StringHelpers
{
++++template<typename+Tuple>
++++using+Formatter+=+std::function<Tuple(const+std::vector<std::string>+&)>;

++++std::vector<std::string>+split(const+std::string+&string,+const+std::string+&delimiter);

++++template<typename+Tuple>
++++std::vector<Tuple>+readCsv(const+std::string+&path,+const+std::string+&delimiter,+Formatter<Tuple>+formatter);
};|code-block|syntax|javascript|4322551|StringsHelpers.cpp|4322552|#include+"StringHelpers.hpp"

namespace+StringHelpers
{
++++/**
+++++*+Split+a+string+with+the+given+delimiter+into+several+strings
+++++*
+++++*+@param+string+-+The+string+to+extract+the+substrings+from
+++++*+@param+delimiter+-+The+substrings+delimiter
+++++*
+++++*+@return+The+substrings
+++++*/
++++std::vector<std::string>+split(const+std::string+&string,+const+std::string+&delimiter)
++++{
++++++++std::vector<std::string>+result;
++++++++size_t+++++++++++++++++++last+=+0,
+++++++++++++++++++++++++++++++++next+=+0;

++++++++while+((next+=+string.find(delimiter,+last))+!=+std::string::npos)+{
++++++++++++result.emplace_back(string.substr(last,+next+-+last));
++++++++++++last+=+next+%2B+1;
++++++++}

++++++++result.emplace_back(string.substr(last));

++++++++return+result;
++++}

++++/**
+++++*+Read+a+CSV+file+and+store+its+values+into+the+given+structure+(Tuple+with+Formatter+constructor)
+++++*
+++++*+@tparam+Tuple+-+The+CSV+line+structure+format
+++++*
+++++*+@param+path+-+The+CSV+file+path
+++++*+@param+delimiter+-+The+CSV+values+delimiter
+++++*+@param+formatter+-+The+CSV+values+formatter+that+take+a+vector+of+strings+in+input+and+return+a+Tuple
+++++*
+++++*+@return+The+CSV+as+vector+of+Tuple
+++++*/
++++template<typename+Tuple>
++++std::vector<Tuple>+readCsv(const+std::string+&path,+const+std::string+&delimiter,+Formatter<Tuple>+formatter)
++++{
++++++++std::ifstream++++++file(path,+std::ifstream::in);
++++++++std::string++++++++line;
++++++++std::vector<Tuple>+result;

++++++++if+(file.fail())+{
++++++++++++throw+std::runtime_error("The+file+"+%2B+path+%2B+"+could+not+be+opened");
++++++++}

++++++++while+(std::getline(file,+line))+{
++++++++++++result.emplace_back(formatter(split(line,+delimiter)));
++++++++}

++++++++file.close();

++++++++return+result;
++++}

++++//+Forward+template+declarations

++++template+std::vector<std::tuple<double,+double,+double>>+readCsv<std::tuple<double,+double,+double>>(const+std::string+&,+const+std::string+&,+Formatter<std::tuple<double,+double,+double>>);
}+//+End+of+StringHelpers+namespace|4322553|main.cpp+(一些用法)|4322554|#include+"StringHelpers.hpp"

/**
+*+Example+of+use+with+a+CSV+file+which+have+(number,Red,Green,Blue)+as+line+values.+We+do+not+want+to+use+the+1st+value
+*+of+the+line.
+*/
int+main(int+argc,+char+**argv)
{
++++//+Declare+CSV+line+type,+formatter+and+template+type
++++typedef+std::tuple<double,+double,+double>++++++++++++++++++++++++++CSV_format;
++++typedef+std::function<CSV_format(const+std::vector<std::string>+&)>+formatterT;

++++enum+RGB+{+Red+=+1,+Green,+Blue+};

++++const+std::string+COLOR_MAP_PATH+=+"/some/absolute/path";

++++//+Load+the+color+map
++++auto+colorMap+=+StringHelpers::readCsv<CSV_format>(COLOR_MAP_PATH,+",",+[](const+std::vector<std::string>+&values)+{
++++++++return+CSV_format+{
++++++++++++++++//+Here+is+the+formatter+lambda+that+convert+each+value+from+string+to+what+you+want
++++++++++++++++std::strtod(values[Red].c_str(),+nullptr),
++++++++++++++++std::strtod(values[Green].c_str(),+nullptr),
++++++++++++++++std::strtod(values[Blue].c_str(),+nullptr)
++++++++};
++++});

++++//+Use+your+colorMap+as+you++wish...
}|4322555|entityMap^0|0|0|0|B|B|N|4|U|9|1H|9|0|0|0|0|I|0|0|0|I|0|0|0|8|0|0^^$0|@$1|2|3|4|5|6|7|17|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|18|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|19|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|1A|8|@$H|1B|I|1C|J|K]|$H|1D|I|1E|J|K]|$H|1F|I|1G|J|K]|$H|1H|I|1I|J|K]]|9|@]|A|$]]|$1|L|3|M|5|6|7|1J|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|1K|8|@]|9|@]|A|$]]|$1|P|3|Q|5|6|7|1L|8|@$H|1M|I|1N|J|R]]|9|@]|A|$]]|$1|S|3|T|5|U|7|1O|8|@]|9|@]|A|$V|W]]|$1|X|3|Y|5|6|7|1P|8|@$H|1Q|I|1R|J|R]]|9|@]|A|$]]|$1|Z|3|10|5|U|7|1S|8|@]|9|@]|A|$V|W]]|$1|11|3|12|5|6|7|1T|8|@$H|1U|I|1V|J|R]]|9|@]|A|$]]|$1|13|3|14|5|U|7|1W|8|@]|9|@]|A|$V|W]]|$1|15|3|-4|5|6|7|1X|8|@]|9|@]|A|$]]]|16|$]]

Like everyone puts his solution, here is mine using template, lambda and tuple.

It can convert any CSV with wanted columns to a C++ vector of tuple.

It works by defining each CSV line element type in a tuple.

You also need to define the <code>std::string</code> to <code>type</code> conversion <code>Formatter</code> lambda for each element (using <code>std::atod</code> for example).

Then you got a vector of this struct corresponding to your CSV data.

You can reuse this easily to match any CSV structure.

StringsHelpers.hpp

<pre class="lang-cpp prettyprint-override"><code>#include &lt;string&gt;
#include &lt;fstream&gt;
#include &lt;vector&gt;
#include &lt;functional&gt;

namespace StringHelpers
{
 template&lt;typename Tuple&gt;
 using Formatter = std::function&lt;Tuple(const std::vector&lt;std::string&gt; &amp;)&gt;;

 std::vector&lt;std::string&gt; split(const std::string &amp;string, const std::string &amp;delimiter);

 template&lt;typename Tuple&gt;
 std::vector&lt;Tuple&gt; readCsv(const std::string &amp;path, const std::string &amp;delimiter, Formatter&lt;Tuple&gt; formatter);
};
</code></pre>

StringsHelpers.cpp

<pre class="lang-cpp prettyprint-override"><code>#include "StringHelpers.hpp"

namespace StringHelpers
{
 /**
 * Split a string with the given delimiter into several strings
 *
 * @param string - The string to extract the substrings from
 * @param delimiter - The substrings delimiter
 *
 * @return The substrings
 */
 std::vector&lt;std::string&gt; split(const std::string &amp;string, const std::string &amp;delimiter)
 {
 std::vector&lt;std::string&gt; result;
 size_t last = 0,
 next = 0;

 while ((next = string.find(delimiter, last)) != std::string::npos) {
 result.emplace_back(string.substr(last, next - last));
 last = next + 1;
 }

 result.emplace_back(string.substr(last));

 return result;
 }

 /**
 * Read a CSV file and store its values into the given structure (Tuple with Formatter constructor)
 *
 * @tparam Tuple - The CSV line structure format
 *
 * @param path - The CSV file path
 * @param delimiter - The CSV values delimiter
 * @param formatter - The CSV values formatter that take a vector of strings in input and return a Tuple
 *
 * @return The CSV as vector of Tuple
 */
 template&lt;typename Tuple&gt;
 std::vector&lt;Tuple&gt; readCsv(const std::string &amp;path, const std::string &amp;delimiter, Formatter&lt;Tuple&gt; formatter)
 {
 std::ifstream file(path, std::ifstream::in);
 std::string line;
 std::vector&lt;Tuple&gt; result;

 if (file.fail()) {
 throw std::runtime_error("The file " + path + " could not be opened");
 }

 while (std::getline(file, line)) {
 result.emplace_back(formatter(split(line, delimiter)));
 }

 file.close();

 return result;
 }

 // Forward template declarations

 template std::vector&lt;std::tuple&lt;double, double, double&gt;&gt; readCsv&lt;std::tuple&lt;double, double, double&gt;&gt;(const std::string &amp;, const std::string &amp;, Formatter&lt;std::tuple&lt;double, double, double&gt;&gt;);
} // End of StringHelpers namespace
</code></pre>

main.cpp (some usage)

<pre class="lang-cpp prettyprint-override"><code>#include "StringHelpers.hpp"

/**
 * Example of use with a CSV file which have (number,Red,Green,Blue) as line values. We do not want to use the 1st value
 * of the line.
 */
int main(int argc, char **argv)
{
 // Declare CSV line type, formatter and template type
 typedef std::tuple&lt;double, double, double&gt; CSV_format;
 typedef std::function&lt;CSV_format(const std::vector&lt;std::string&gt; &amp;)&gt; formatterT;

 enum RGB { Red = 1, Green, Blue };

 const std::string COLOR_MAP_PATH = "/some/absolute/path";

 // Load the color map
 auto colorMap = StringHelpers::readCsv&lt;CSV_format&gt;(COLOR_MAP_PATH, ",", [](const std::vector&lt;std::string&gt; &amp;values) {
 return CSV_format {
 // Here is the formatter lambda that convert each value from string to what you want
 std::strtod(values[Red].c_str(), nullptr),
 std::strtod(values[Green].c_str(), nullptr),
 std::strtod(values[Blue].c_str(), nullptr)
 };
 });

 // Use your colorMap as you wish...
}
</code></pre>

blocks|key|115458|text|@sastanin的解决方案的一个次要版本，这样它就可以处理引号中的换行符。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|115459|std::vector<std::vector<std::string>>+readCSV(std::istream+&in)+{
++++std::vector<std::vector<std::string>>+table;

++++while+(!in.eof())+{
++++++++CSVState+state+=+CSVState::UnquotedField;
++++++++std::vector<std::string>+fields+{""};
++++++++size_t+i+=+0;+//+index+of+the+current+field
++++++++for+(char+c+:+row)+{
++++++++++++switch+(state)+{
++++++++++++++++case+CSVState::UnquotedField:
++++++++++++++++++++switch+(c)+{
++++++++++++++++++++++++case+',':+//+end+of+field
++++++++++++++++++++++++++++++++++fields.push_back("");+i%2B%2B;
++++++++++++++++++++++++++++++++++break;
++++++++++++++++++++++++case+'"':+state+=+CSVState::QuotedField;
++++++++++++++++++++++++++++++++++break;
++++++++++++++++++++++++default:++fields[i].push_back(c);
++++++++++++++++++++++++++++++++++break;+}
++++++++++++++++++++break;
++++++++++++++++case+CSVState::QuotedField:
++++++++++++++++++++switch+(c)+{
++++++++++++++++++++++++case+'"':+state+=+CSVState::QuotedQuote;
++++++++++++++++++++++++++++++++++break;
++++++++++++++++++++++++default:++fields[i].push_back(c);
++++++++++++++++++++++++++++++++++break;+}
++++++++++++++++++++break;
++++++++++++++++case+CSVState::QuotedQuote:
++++++++++++++++++++switch+(c)+{
++++++++++++++++++++++++case+',':+//+,+after+closing+quote
++++++++++++++++++++++++++++++++++fields.push_back("");+i%2B%2B;
++++++++++++++++++++++++++++++++++state+=+CSVState::UnquotedField;
++++++++++++++++++++++++++++++++++break;
++++++++++++++++++++++++case+'"':+//+""+->+"
++++++++++++++++++++++++++++++++++fields[i].push_back('"');
++++++++++++++++++++++++++++++++++state+=+CSVState::QuotedField;
++++++++++++++++++++++++++++++++++break;
++++++++++++++++++++++++case+'\n':+//+newline
++++++++++++++++++++++++++++++++++table.push_back(fields);
++++++++++++++++++++++++++++++++++state+=+CSVState::UnquotedField;
++++++++++++++++++++++++++++++++++fields+=+vector<string>{""};
++++++++++++++++++++++++++++++++++i+=+0;
++++++++++++++++++++++++default:++//+end+of+quote
++++++++++++++++++++++++++++++++++state+=+CSVState::UnquotedField;
++++++++++++++++++++++++++++++++++break;+}
++++++++++++++++++++break;
++++++++++++}
++++++++}
++++}
++++return+table;
}|code-block|syntax|javascript|115460|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

A minor edition to @sastanin's solution, so that it can deal with newlines within quotes.

<pre class="lang-cpp prettyprint-override"><code>std::vector&lt;std::vector&lt;std::string&gt;&gt; readCSV(std::istream &amp;in) {
 std::vector&lt;std::vector&lt;std::string&gt;&gt; table;

 while (!in.eof()) {
 CSVState state = CSVState::UnquotedField;
 std::vector&lt;std::string&gt; fields {""};
 size_t i = 0; // index of the current field
 for (char c : row) {
 switch (state) {
 case CSVState::UnquotedField:
 switch (c) {
 case ',': // end of field
 fields.push_back(""); i++;
 break;
 case '"': state = CSVState::QuotedField;
 break;
 default: fields[i].push_back(c);
 break; }
 break;
 case CSVState::QuotedField:
 switch (c) {
 case '"': state = CSVState::QuotedQuote;
 break;
 default: fields[i].push_back(c);
 break; }
 break;
 case CSVState::QuotedQuote:
 switch (c) {
 case ',': // , after closing quote
 fields.push_back(""); i++;
 state = CSVState::UnquotedField;
 break;
 case '"': // "" -&gt; "
 fields[i].push_back('"');
 state = CSVState::QuotedField;
 break;
 case '\n': // newline
 table.push_back(fields);
 state = CSVState::UnquotedField;
 fields = vector&lt;string&gt;{""};
 i = 0;
 default: // end of quote
 state = CSVState::UnquotedField;
 break; }
 break;
 }
 }
 }
 return table;
}
</code></pre>

blocks|key|1105926|text|由于解析Excel格式的CSV不是一项简单的任务，我想在这里添加我的代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1105927|http://fgw.ddnss.de/CSV_Endlicher_Automat.html|offset|length|1105928|这是一个确定性状态机，它显式地处理所有情况(普通的、引号的、引号的转义)，没有任何奇怪的攻击。|1105929|我确实认为上面的一些“解决方案”是不正确的，有些是过于复杂的。|1105930|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|1A|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@$D|S|E|T|1|U]]|A|$]]|$1|F|3|G|5|6|7|V|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|C]]]]

As parsing Excel-formatted CSVs is not a trivial task, I would like to add code of mine here:
<a href="http://fgw.ddnss.de/CSV_Endlicher_Automat.html" rel="nofollow noreferrer">http://fgw.ddnss.de/CSV_Endlicher_Automat.html</a>
This is a deterministic state machine, which handles all cases (plain, quoting, escaping of quotes) explicitly and without any strange hacks.
I do think several &quot;solutions&quot; above are incorrect and some are excessively complex.

blocks|key|1105955|text|您可以使用仅包含头的Csv::Parser库。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1105956|1105957|它完全支持RFC4180，包括引号、转义引号和字段值中的换行符。|unordered-list-item|1105958|它只需要标准的C%2B%2B+(C%2B%2B17)。|1105959|它支持从使用RFC4180进行广泛测试的compile-time.|1105960|It's的std::string_view中读取CSV数据|style|CODE|1105961|1105962|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/ashaduri/csv-parser^0|A|B|0|0|0|0|0|0|5|G|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@$A|Z|B|10|1|11]]|C|$]]|$1|D|3|-4|5|6|7|12|8|@]|9|@]|C|$]]|$1|E|3|F|5|G|7|13|8|@]|9|@]|C|$]]|$1|H|3|I|5|G|7|14|8|@]|9|@]|C|$]]|$1|J|3|K|5|G|7|15|8|@]|9|@]|C|$]]|$1|L|3|M|5|G|7|16|8|@$A|17|B|18|N|O]]|9|@]|C|$]]|$1|P|3|-4|5|6|7|19|8|@]|9|@]|C|$]]|$1|Q|3|-4|5|6|7|1A|8|@]|9|@]|C|$]]]|R|$S|$5|T|U|V|C|$W|X]]]]

You can use the header-only <a href="https://github.com/ashaduri/csv-parser" rel="nofollow noreferrer">Csv::Parser</a> library.
<ul>
<li>It fully supports RFC 4180, including quoted values, escaped quotes, and newlines in field values.</li>
<li>It requires only standard C++ (C++17).</li>
<li>It supports reading CSV data from <code>std::string_view</code> at compile-time.</li>
<li>It's extensively tested using <a href="https://github.com/catchorg/Catch2" rel="nofollow noreferrer">Catch2</a>.</li>
</ul>

blocks|key|115525|text|CSV文件是由行组成的文本文件，每行由逗号表示的标记组成。在解析时，有一些事情你应该知道：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|115526|(0)使用"CP_ACP“代码页对文件进行编码。您应该使用相同的编码页面来解码文件内容。|115527|(1)+CSV丢失了“复合单元格”信息(如rowspan+>+1)，因此当它被读回到excel时，复合单元格信息就丢失了。|115528|(2)单元格文本可以在头部和尾部用“”引号，文字引号字符将变成双引号。因此，闭合匹配的引号字符必须是引号字符，后面不能跟其他引号字符。例如，如果一个单元格有逗号，则必须在csv中使用引号，因为逗号在csv中有意义。|115529|(3)当单元格内容有多行时，会在CSV中引用，这种情况下，解析器必须继续读取CSV文件中的下几行，直到得到与第一个引号字符匹配的右引号字符，在解析该行的标记之前，请确保当前逻辑行已读取完毕。|115530|例如:在csv文件中，以下3行物理行是由3个标记组成的一条逻辑行：|115531|++++--%2B----------
++++1+%7Ca,"b-first+part
++++2+%7Cb-second+part
++++3+%7Cb-third+part",c
++++--%2B----------|code-block|syntax|javascript|115532|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|V|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|X|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|Y|8|@]|9|@]|A|$O|P]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

CSV file are text files consist of lines, each line is consist of tokens sererated by comma. while there are something you should know when parsing:
(0) The file is encoded with &quot;CP_ACP&quot; code page. you should use the same encoding page to decode the file contents.
(1) the CSV lost &quot;composite cells&quot; information (likes rowspan &gt; 1) , so when it is read back to excel, the composite cell information is lost.
(2) the cell text can be quoted by &quot;&quot;&quot; at head and tail, and literal quote char will become double quotes. so the closing matching quote char must be a quote char not followed by another quote char. for eg, if a cell has a comma, it must be quoted in csv, because comma make sense in csv.
(3) when the cell content have multiple lines, it will be quoted in CSV, in this case, you parser must keep reading next sereral lines in CSV file, until you got a closing quote char matching the first quote char, make sure the current logical line is read complete before parsing the line's tokens.
for eg: in csv file, the following 3 physical lines is one logical line consist of 3 tokens:
<pre><code> --+----------
 1 |a,&quot;b-first part
 2 |b-second part
 3 |b-third part&quot;,c
 --+----------
</code></pre>

I need to load and use CSV file data in C++. At this point it can really just be a comma-delimited parser (ie don't worry about escaping new lines and commas). The main need is a line-by-line parser that will return a vector for the next line each time the method is called.

I found this article which looks quite promising:
<a href="http://www.boost.org/doc/libs/1_35_0/libs/spirit/example/fundamental/list_parser.cpp" rel="noreferrer">http://www.boost.org/doc/libs/1_35_0/libs/spirit/example/fundamental/list_parser.cpp</a>

I've never used Boost's Spirit, but am willing to try it. But only if there isn't a more straightforward solution I'm overlooking.

How can I read and parse CSV files in C++?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我需要在C++中加载和使用CSV文件数据。在这一点上，它实际上可以只是一个逗号分隔的解析器(即不用担心转义新行和逗号)。主要需要的是逐行解析器，它将在每次调用方法时返回下一行的向量。我发现这篇文章看起来很有前途：我从来没有用过Boost的精神，但我愿意尝试一下。但前提是没有我忽略的更直接的解决方案。

问如何在C++中读取和解析CSV文件？
EN

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问如何在C++中读取和解析CSV文件？EN