blocks|key|709|text|您可以使用stringstream。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|710|#include+<sstream>

//+...
std::string+number;
std::stringstream+strstream;
strstream+<<+1L;
strstream+>>+number;|code-block|syntax|javascript|711|通常在编译器的标准库中也有一些专有的C函数可以做到这一点。不过，我更喜欢“可移植”的变体。|712|C语言的方法是使用sprintf，但这并不是很安全。在一些库中，有像sprintf_s这样的新版本，它可以防止缓冲区溢出。|713|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]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You could use stringstream.

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

// ...
std::string number;
std::stringstream strstream;
strstream &lt;&lt; 1L;
strstream &gt;&gt; number;
</code></pre>

There is usually some proprietary C functions in the standard library for your compiler that does it too. I prefer the more "portable" variants though.

The C way to do it would be with sprintf, but that is not very secure. In some libraries there is new versions like sprintf_s which protects against buffer overruns.

blocks|key|875388|text|在C%2B%2B11中，实际上有std::to_string和std::to_wstring函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|875389|string+to_string(int+val);
string+to_string(long+val);
string+to_string(long+long+val);
string+to_string(unsigned+val);
string+to_string(unsigned+long+val);
string+to_string(unsigned+long+long+val);
string+to_string(float+val);
string+to_string(double+val);
string+to_string+(long+double+val);|code-block|syntax|javascript|875390|entityMap|0|LINK|mutability|MUTABLE|url|https://en.cppreference.com/w/cpp/string/basic_string/to_string|1|https://en.cppreference.com/w/cpp/string/basic_string/to_wstring^0|C|E|0|R|F|1|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]|$A|W|B|X|1|Y]]|C|$]]|$1|D|3|E|5|F|7|Z|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|10|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]|Q|$5|L|M|N|C|$O|R]]]]

In C++11, there are actually <a href="https://en.cppreference.com/w/cpp/string/basic_string/to_string" rel="nofollow noreferrer">std::to_string</a> and <a href="https://en.cppreference.com/w/cpp/string/basic_string/to_wstring" rel="nofollow noreferrer">std::to_wstring</a> functions in &lt;string&gt;.
<pre><code>string to_string(int val);
string to_string(long val);
string to_string(long long val);
string to_string(unsigned val);
string to_string(unsigned long val);
string to_string(unsigned long long val);
string to_string(float val);
string to_string(double val);
string to_string (long double val);
</code></pre>

blocks|key|875143|text|如果你是copy-paste的粉丝，这里有：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|875144|#include+<sstream>

template+<class+T>
inline+std::string+to_string+(const+T&+t)
{
++++std::stringstream+ss;
++++ss+<<+t;
++++return+ss.str();
}|code-block|syntax|javascript|875145|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|$]]

Well if you are fan of copy-paste, here it is:

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

template &lt;class T&gt;
inline std::string to_string (const T&amp; t)
{
 std::stringstream ss;
 ss &lt;&lt; t;
 return ss.str();
}
</code></pre>

blocks|key|1301234|text|点击此处了解boost::lexical_cast<std::string>(my_long)更多信息http://www.boost.org/doc/libs/1_39_0/libs/conversion/lexical_cast.htm|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1301235|entityMap|0|LINK|mutability|MUTABLE|url|http://www.boost.org/doc/libs/1_39_0/libs/conversion/lexical_cast.htm^0|6|15|1F|1X|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

<code>boost::lexical_cast&lt;std::string&gt;(my_long)</code>
more here <a href="http://www.boost.org/doc/libs/1_39_0/libs/conversion/lexical_cast.htm" rel="noreferrer">http://www.boost.org/doc/libs/1_39_0/libs/conversion/lexical_cast.htm</a>

blocks|key|875109|text|int+main()
{
++++long+mylong+=+123456789;
++++string+mystring;
++++stringstream+mystream;
++++mystream+<<+mylong;
++++mystring+=+mystream.str();
++++cout+<<+mystring+<<+"\n";
++++return+0;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|875110|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>int main()
{
 long mylong = 123456789;
 string mystring;
 stringstream mystream;
 mystream &lt;&lt; mylong;
 mystring = mystream.str();
 cout &lt;&lt; mystring &lt;&lt; "\n";
 return 0;
}
</code></pre>

blocks|key|468|text|您可以在C%2B%2B11中使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|469|long+val+=+12345;
std::string+my_val+=+std::to_string(val);|code-block|syntax|javascript|470|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 use <a href="http://en.cppreference.com/w/cpp/string/basic_string/to_string" rel="noreferrer">std::to_string</a> in C++11

<pre><code>long val = 12345;
std::string my_val = std::to_string(val);
</code></pre>

blocks|key|1303615|text|我不知道这是什么类型的作业，但很可能老师不想要你只是调用一个“神奇的”现有函数的答案(尽管这是推荐的方法)，但他想看看你是否可以自己实现它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1303616|回到过去，我的老师经常说这样的话：“我想看看你是否能自己编程，而不是你能不能在系统中找到它。”好吧，他错了多少;)+..|1303617|不管怎么说，如果你的老师也是这样的，下面是最难的方法。|1303618|std::string+LongToString(long+value)
{
++std::string+output;
++std::string+sign;

++if(value+<+0)
++{
++++sign+%2B+"-";
++++value+=+-value;
++}

++while(output.empty()+%7C%7C+(value+>+0))
++{
++++output.push_front(value+%25+10+%2B+'0')
++++value+/=+10;
++}

++return+sign+%2B+output;
}|code-block|syntax|javascript|1303619|你可能会争辩说，使用std::string并不是“困难的方式”，但我猜实际算法中最重要的是什么。|offset|length|style|CODE|1303620|entityMap^0|0|0|0|0|A|B|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|V|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|W|8|@$M|X|N|Y|O|P]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I don't know what kind of homework this is, but most probably the teacher doesn't want an answer where you just call a "magical" existing function (even though that's the recommended way to do it), but he wants to see if you can implement this by your own.

Back in the days, my teacher used to say something like "I want to see if you can program by yourself, not if you can find it in the system." Well, how wrong he was ;) ..

Anyway, if your teacher is the same, here is the hard way to do it..

<pre><code>std::string LongToString(long value)
{
 std::string output;
 std::string sign;

 if(value &lt; 0)
 {
 sign + "-";
 value = -value;
 }

 while(output.empty() || (value &gt; 0))
 {
 output.push_front(value % 10 + '0')
 value /= 10;
 }

 return sign + output;
}
</code></pre>

You could argue that using <code>std::string</code> is not "the hard way", but I guess what counts in the actual agorithm.

blocks|key|1301202|text|有几种方法。请阅读The+String+Formatters+of+Manor+Farm以进行深入比较。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1301203|entityMap|0|LINK|mutability|MUTABLE|url|http://www.gotw.ca/publications/mill19.htm^0|9|Z|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

There are several ways. Read <a href="http://www.gotw.ca/publications/mill19.htm" rel="nofollow noreferrer">The String Formatters of Manor Farm</a> for an in-depth comparison.

blocks|key|333|text|+++#include+<sstream>


+++....

++++std::stringstream+ss;
++++ss+<<+a_long_int;++//+or+any+other+type
++++std::string+result=ss.str();+++//+use+.str()+to+get+a+string+back|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|334|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> #include &lt;sstream&gt;


 ....

 std::stringstream ss;
 ss &lt;&lt; a_long_int; // or any other type
 std::string result=ss.str(); // use .str() to get a string back
</code></pre>

blocks|key|1301167|text|查看std::stringstream。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1301168|entityMap^0|2|H|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

Check out <code>std::stringstream</code>.

blocks|key|441|text|到目前为止，为了帮助你进一步思考这个问题，有一件事没有被任何人涉及到，那就是当它被转换为字符串时，什么格式应该花很长的时间。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|442|只需看一下电子表格程序(如Calc/Excel)。您是否希望将其四舍五入到最接近的百万，如果为负数，则使用括号，始终显示符号...这个数字真的是其他东西的表示吗?你应该用Oractal还是Hex来表示它？|443|到目前为止，答案已经给出了一些默认输出，但可能不是正确的。|444|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

One of the things not covered by anybody so far, to help you think about the problem further, is what format should a long take when it is cast to a string.

Just have a look at a spreedsheet program (like Calc/Excel). Do you want it rounded to the nearest million, with brackets if it's negative, always to show the sign.... Is the number realy a representation of something else, should you show it in Oractal or Hex instead?

The answers so far have given you some default output, but perhaps not the right ones.

blocks|key|4093330|text|我通常使用sprintf来做这件事。因此，在很长一段时间内，假设您使用的是32位架构，则可以执行以下操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4093331|char+buf[5]+=+{0};+//+one+extra+byte+for+null++++
sprintf(buf,+"%25l",+var_for_long);|code-block|syntax|javascript|4093332|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|$]]

The way I typically do it is with sprintf. So for a long you could do the following assuming that you are on a 32 bit architecture:

<pre><code>char buf[5] = {0}; // one extra byte for null 
sprintf(buf, "%l", var_for_long);
</code></pre>

How do I convert a <code>long</code> to a <code>string</code> in C++?

How do I convert a long to a string 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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问如何在C++中将long转换为字符串？
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问如何在C++中将long转换为字符串？
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