blocks|key|1717019|text|从stdin读取可变数量的数据的唯一方法是使用循环。我总是发现std::getline()函数工作得很好：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1717020|std::string+line;
while+(std::getline(std::cin,+line))
{
++++std::cout+<<+line+<<+std::endl;
}|code-block|syntax|javascript|1717021|默认情况下，getline()会一直读到换行符。您可以指定另一个终止字符，但是EOF本身不是一个字符，因此您不能简单地调用一次getline()。|1717022|entityMap|0|LINK|mutability|MUTABLE|url|http://en.cppreference.com/w/cpp/string/basic_string/getline^0|1|5|V|E|V|E|0|0|0|6|9|1R|9|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$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|@$9|14|A|15|B|C]|$9|16|A|17|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

The only way you can read a variable amount of data from <code>stdin</code> is using loops. I've always found that the <a href="http://en.cppreference.com/w/cpp/string/basic_string/getline" rel="noreferrer"><code>std::getline()</code></a> function works very well:

<pre><code>std::string line;
while (std::getline(std::cin, line))
{
 std::cout &lt;&lt; line &lt;&lt; std::endl;
}
</code></pre>

By default <code>getline()</code> reads until a newline. You can specify an alternative termination character, but EOF is not itself a character so you cannot simply make one call to <code>getline()</code>.

blocks|key|1502026|text|使用循环：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1502027|#include+<iostream>
using+namespace+std;
...
//+numbers
int+n;
while+(cin+>>+n)
{
+++...
}
//+lines
string+line;
while+(getline(cin,+line))
{
+++...
}
//+characters
char+c;
while+(cin.get(c))
{
+++...
}|code-block|syntax|javascript|1502028|resource|offset|length|1502029|entityMap|0|LINK|mutability|MUTABLE|url|http://acm.timus.ru/help.aspx?topic=cpp^0|0|0|0|8|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

Using loops:

<pre><code>#include &lt;iostream&gt;
using namespace std;
...
// numbers
int n;
while (cin &gt;&gt; n)
{
 ...
}
// lines
string line;
while (getline(cin, line))
{
 ...
}
// characters
char c;
while (cin.get(c))
{
 ...
}
</code></pre>

<a href="http://acm.timus.ru/help.aspx?topic=cpp" rel="noreferrer">resource</a>

blocks|key|1501989|text|通过使用流迭代器，您可以在没有显式循环的情况下完成此操作。我确信它在内部使用了某种循环。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1501990|#include+<string>
#include+<iostream>
#include+<istream>
#include+<ostream>
#include+<iterator>

int+main()
{
//+don't+skip+the+whitespace+while+reading
++std::cin+>>+std::noskipws;

//+use+stream+iterators+to+copy+the+stream+to+a+string
++std::istream_iterator<char>+it(std::cin);
++std::istream_iterator<char>+end;
++std::string+results(it,+end);

++std::cout+<<+results;
}|code-block|syntax|javascript|1501991|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|$]]

You can do it without explicit loops by using stream iterators. I'm sure that it uses some kind of loop internally.

<pre><code>#include &lt;string&gt;
#include &lt;iostream&gt;
#include &lt;istream&gt;
#include &lt;ostream&gt;
#include &lt;iterator&gt;

int main()
{
// don't skip the whitespace while reading
 std::cin &gt;&gt; std::noskipws;

// use stream iterators to copy the stream to a string
 std::istream_iterator&lt;char&gt; it(std::cin);
 std::istream_iterator&lt;char&gt; end;
 std::string results(it, end);

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

blocks|key|1717380|text|在使用std::istream_iterator研究了KeithB的解决方案后，我发现了std:istreambuf_iterator。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1717381|测试程序将所有管道输入读取为一个字符串，然后再次将其写出：|1717382|#include+<iostream>
#include+<iterator>
#include+<string>

int+main()
{
++std::istreambuf_iterator<char>+begin(std::cin),+end;
++std::string+s(begin,+end);
++std::cout+<<+s;
}|code-block|syntax|javascript|1717383|entityMap|0|LINK|mutability|MUTABLE|url|http://en.cppreference.com/w/cpp/iterator/istreambuf_iterator^0|3|L|18|N|18|N|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|6|7|12|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|13|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

After researching KeithB's solution using <code>std::istream_iterator</code>, I discovered the <a href="http://en.cppreference.com/w/cpp/iterator/istreambuf_iterator" rel="noreferrer"><code>std:istreambuf_iterator</code></a>.

Test program to read all piped input into a string, then write it out again:

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

int main()
{
 std::istreambuf_iterator&lt;char&gt; begin(std::cin), end;
 std::string s(begin, end);
 std::cout &lt;&lt; s;
}
</code></pre>

blocks|key|1502202|text|可能是最简单且通常最有效的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1502203|#include+<iostream>
int+main()
{
++++std::cout+<<+std::cin.rdbuf();
}|code-block|syntax|javascript|1502204|如果需要，可以使用std::ostringstream等其他类型的流作为缓冲区，而不是这里的标准输出流。|offset|length|style|CODE|1502205|entityMap^0|0|0|9|I|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Probable simplest and generally efficient:

<pre><code>#include &lt;iostream&gt;
int main()
{
 std::cout &lt;&lt; std::cin.rdbuf();
}
</code></pre>

If needed, use stream of other types like <code>std::ostringstream</code> as buffer instead of standard output stream here.

blocks|key|1717203|text|可悲的附注:我决定使用C%2B%2B+IO来与基于boost的代码保持一致。从这个问题的答案中，我选择了while+(std::getline(std::cin,+line))。在cygwin+(mintty)中使用g%2B%2B版本4.5.3+(-O3)，我得到了2MB/s的吞吐量。微软Visual+C%2B%2B+2010+(/O2)使相同代码的速度达到40+MB/s。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1717204|在将IO重写为纯C+while+(fgets(buf,+100,+stdin))后，两个测试编译器的吞吐量都跃升至90MB/s。这对大于10MB的任何输入都是有影响的…|1717205|entityMap^0|1C|10|0|A|U|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|P|8|@]|D|@]|E|$]]]|I|$]]

Sad side note: I decided to use C++ IO to be consistent with boost based code. From answers to this question I chose <code>while (std::getline(std::cin, line))</code>. Using g++ version 4.5.3 (-O3) in cygwin (mintty) i got 2 MB/s throughput. Microsoft Visual C++ 2010 (/O2) made it 40 MB/s for the same code.

After rewriting the IO to pure C <code>while (fgets(buf, 100, stdin))</code> the throughput jumped to 90 MB/s in both tested compilers. That makes a difference for any input bigger than 10 MB...

blocks|key|1716980|text|您可以使用std::istream::getline()+(或者最好是version+that+works+on+std::string)函数来获取整个行。这两个版本都允许您指定分隔符(行尾字符)。字符串版本的默认值为'\n‘。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1716981|entityMap|0|LINK|mutability|MUTABLE|url|http://www.cplusplus.com/reference/iostream/istream/getline.html|1|http://www.cppreference.com/wiki/string/getline^0|5|N|0|Z|X|1|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]|$A|R|B|S|1|T]]|C|$]]|$1|D|3|-4|5|6|7|U|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]|L|$5|G|H|I|C|$J|M]]]]

You can use the <a href="http://www.cplusplus.com/reference/iostream/istream/getline.html" rel="nofollow noreferrer">std::istream::getline()</a> (or preferably the <a href="http://www.cppreference.com/wiki/string/getline" rel="nofollow noreferrer">version that works on std::string</a>) function to get an entire line. Both have versions that allow you to specify the delimiter (end of line character). The default for the string version is '\n'.

blocks|key|1717145|text|while(std::cin)+{
+//+do+something
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1717146|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>while(std::cin) {
 // do something
}
</code></pre>

blocks|key|1717304|text|等等，我没理解错吧？您正在使用cin进行键盘输入，并且希望在用户输入EOF字符时停止读取输入？为什么用户要键入EOF字符？或者你的意思是你想停止读取EOF上的文件？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1717305|如果您实际上正在尝试使用cin来读取EOF字符，那么为什么不将EOF指定为分隔符呢？|1717306|//+Needed+headers:+iostream

char+buffer[256];
cin.get(+buffer,+'\x1A'+);|code-block|syntax|javascript|1717307|如果您想在EOF处停止读取文件，那么只需使用getline并再次指定EOF作为分隔符。|1717308|//+Needed+headers:+iostream,+string,+and+fstream

string+buffer;

++++ifstream+fin;
++++fin.open("test.txt");
++++if(fin.is_open())+{
++++++++getline(fin,buffer,'\x1A');

++++++++fin.close();
++++}|1717309|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Wait, am I understanding you correctly? You're using cin for keyboard input, and you want to stop reading input when the user enters the EOF character? Why would the user ever type in the EOF character? Or did you mean you want to stop reading from a file at the EOF?

If you're actually trying to use cin to read an EOF character, then why not just specify the EOF as the delimiter?

<pre><code>// Needed headers: iostream

char buffer[256];
cin.get( buffer, '\x1A' );
</code></pre>

If you mean to stop reading from a file at the EOF, then just use getline and once again specify the EOF as the delimiter.

<pre><code>// Needed headers: iostream, string, and fstream

string buffer;

 ifstream fin;
 fin.open("test.txt");
 if(fin.is_open()) {
 getline(fin,buffer,'\x1A');

 fin.close();
 }
</code></pre>

I am coding a program that reads data directly from user input and was wondering how could I (without loops) read all data until EOF from standard input. I was considering using <code>cin.get( input, '\0' )</code> but <code>'\0'</code> is not really the EOF character, that just reads until EOF or <code>'\0'</code>, whichever comes first.

Or is using loops the only way to do it? If so, what is the best way?

How to read until EOF from cin in C++

编译器

我正在编写一个直接从用户输入读取数据的程序，我想知道如何(没有循环)从标准输入读取所有数据，直到EOF。我在考虑使用cin.get( input, '\0' )，但'\0'并不是真正的EOF字符，它只读到EOF或'\0'，无论哪个先出现。或者使用循环是唯一的方法吗？如果是这样，最好的方法是什么？

问如何在C++中从cin读取到EOF
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问如何在C++中从cin读取到EOF
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