blocks|key|2306368|text|你的版本似乎是最新的，所以不应该有问题。我认为这可能与gcc有关。尝试g%2B%2B。(很可能是自动链接问题。如果您只是在C%2B%2B文件上运行gcc，它就不会像g%2B%2B那样“正常工作”。这是因为它不会自动链接到C%2B%2B+std库等等)。我的第二个建议是试试std::atoi。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2306369|@我已经解决了这个问题。std::stoi使用libstdc%2B%2B。它是关于的GNU标准C%2B%2B库。在gcc中，您必须链接添加-lstdc%2B%2B。然而，在g%2B%2B中，libstdc%2B%2B是自动链接的。gcc和使用g%2B%2B|BOLD|2306370|注意它是如何编译的|2306371|使用g%2B%2B：g%2B%2B+-std=c%2B%2B11+-O3+-Wall+-pedantic+main.cpp+&&+./a.out|2306372|使用gcc：gcc+-std=c%2B%2B11+-O3+-Wall+-pedantic+-lstdc%2B%2B+main.cpp+&&+./a.out|2306373|我认为你应该设置像set(CMAKE_EXE_LINKER_FLAGS+"-libgcc+-lstdc%2B%2B")这样的标志(没有测试)|2306374|#include+<cstdlib>

int+myInt+=+std::atoi(test.c_str());|code-block|syntax|javascript|2306375|entityMap|0|LINK|mutability|MUTABLE|url|http://coliru.stacked-crooked.com/a/e868551c74002ba0|1|http://coliru.stacked-crooked.com/a/5e7fd427615447e5^0|R|3|Z|3|3C|9|0|C|9|1D|3|1P|8|N|9|11|A|27|9|2N|3|0|2R|5|1|0|0|6|1I|0|6|1R|0|9|1A|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@$9|16|A|17|B|C]|$9|18|A|19|B|C]|$9|1A|A|1B|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1C|8|@$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]|$9|1J|A|1K|B|H]|$9|1L|A|1M|B|H]|$9|1N|A|1O|B|H]]|D|@$9|1P|A|1Q|1|1R]|$9|1S|A|1T|1|1U]]|E|$]]|$1|I|3|J|5|6|7|1V|8|@]|D|@]|E|$]]|$1|K|3|L|5|6|7|1W|8|@$9|1X|A|1Y|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|1Z|8|@$9|20|A|21|B|C]]|D|@]|E|$]]|$1|O|3|P|5|6|7|22|8|@$9|23|A|24|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|S|7|25|8|@]|D|@]|E|$T|U]]|$1|V|3|-4|5|6|7|26|8|@]|D|@]|E|$]]]|W|$X|$5|Y|Z|10|E|$11|12]]|13|$5|Y|Z|10|E|$11|14]]]]

Your version seems up to date, so there shouldn't be an issue. I think it may be related to <code>gcc</code>. Try <code>g++</code> instead.(Most likely automatically linking issue. If you just run gcc on a C++ file, it will not 'just work' like g++ does. That's because it won't automatically link to the C++ std library, etc.). My second advise is try <code>std::atoi</code>. 

@ I have fixed the issue. <code>std::stoi</code> uses libstdc++. It is about The GNU Standard C++ Library. In <code>gcc</code> you have to link adding <code>-lstdc++</code>. However, in g++, libstdc++ is linked automatically.
<a href="http://coliru.stacked-crooked.com/a/e868551c74002ba0" rel="nofollow">using gcc</a> and <a href="http://coliru.stacked-crooked.com/a/5e7fd427615447e5" rel="nofollow">using g++</a>

Pay attention how it is compiled

using g++: <code>g++ -std=c++11 -O3 -Wall -pedantic main.cpp &amp;&amp; ./a.out</code>

using gcc: <code>gcc -std=c++11 -O3 -Wall -pedantic -lstdc++ main.cpp &amp;&amp; ./a.out</code>

I think you should set flag like <code>set(CMAKE_EXE_LINKER_FLAGS "-libgcc -lstdc++")</code> (Not tested)

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

int myInt = std::atoi(test.c_str());
</code></pre>

blocks|key|2306423|text|在libstdc%2B%2B中，stoi、stol等的定义以及to_string函数都由条件保护。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2306424|#if+((__cplusplus+>=+201103L)+&&+defined(_GLIBCXX_USE_C99)+\
+++++&&+!defined(_GLIBCXX_HAVE_BROKEN_VSWPRINTF))|code-block|syntax|javascript|2306425|我以前在一个平台(即安卓上的Termux+)上遇到过这种失败，导致to_string甚至在g%2B%2B+6.1和C%2B%2B14标准中都不可用。在这种情况下，我刚刚做了|2306426|#define+_GLIBCXX_USE_C99+1|2306427|在包括任何东西之前，突然之间，功能就存在了。(您应该将它放在命令行中，而不是在包含<string>之前，因为另一个头可能首先包含<string>，然后它的包含保护将阻止它看到您的宏。)|2306428|我没有调查为什么这个宏一开始就没有被设置。显然，如果您希望您的代码实际工作(在我的例子中，我不是特别的，但是FWIW没有问题)，这是一个值得关注的问题。|2306429|您应该检查_GLIBCXX_USE_C99是否未定义，或者是否定义了_GLIBCXX_HAVE_BROKEN_VSWPRINTF+(在MinGW上可能是这样吗？)|2306430|entityMap^0|C|4|H|4|R|9|0|0|X|9|0|0|15|8|1S|8|0|0|5|G|Y|U|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1D|8|@]|D|@]|E|$]]|$1|S|3|T|5|6|7|1E|8|@$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|U|3|-4|5|6|7|1J|8|@]|D|@]|E|$]]]|V|$]]

In libstdc++, the definitions of <code>stoi</code>, <code>stol</code>, etc., as well as the <code>to_string</code> functions, are guarded by the condition

<pre><code>#if ((__cplusplus &gt;= 201103L) &amp;&amp; defined(_GLIBCXX_USE_C99) \
 &amp;&amp; !defined(_GLIBCXX_HAVE_BROKEN_VSWPRINTF))
</code></pre>

I have had this fail on one platform before (namely Termux on Android), resulting in <code>to_string</code> not being available even with g++ 6.1 and the C++14 standard. In that case, I just did

<pre><code>#define _GLIBCXX_USE_C99 1
</code></pre>

before including anything, and voilà, suddenly the functions existed. (You should put this first, or even on the command line, rather than just before including <code>&lt;string&gt;</code>, because another header may include <code>&lt;string&gt;</code> first, and then its include guards will keep it from ever seeing your macro.)

I did not investigate why this macro wasn't set in the first place. Obviously this is a cause for concern if you want your code to actually work (in my case I didn't particularly, but FWIW there were no problems.)

You should check if <code>_GLIBCXX_USE_C99</code> is not defined, or if <code>_GLIBCXX_HAVE_BROKEN_VSWPRINTF</code> is defined (which may be the case on MinGW?)

blocks|key|1181283|text|斯泰是一种C%2B%2B11函数。您必须使用-std=c%2B%2B11在g%2B%2B和clang%2B%2B中启用它。这是实际问题，而不是链接错误或特定的预处理器定义。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1181284|+$+cat+test.cxx
#include+<iostream>
#include+<string>

int+main()
{
++++std::string+test+=+"45";
++++int+myint+=+std::stoi(test);
++++std::cout+<<+myint+<<+'\n';
}
+$+g%2B%2B+-otest+test.cxx
test.cxx:+In+Funktion+»int+main()«:
test.cxx:7:17:+Fehler:+»stoi«+ist+kein+Element+von+»std«
+++++int+myint+=+std::stoi(test);
+++++++++++++++++%5E
+$+g%2B%2B+-otest+test.cxx+-std=c%2B%2B11
+$+./test
45
+$|code-block|syntax|javascript|1181285|编辑:我刚刚看到你使用了c%2B%2B11。你确定这是你的编译选项吗？检查生成的makefile并观察执行的命令是否确定。|1181286|entityMap|0|LINK|mutability|MUTABLE|url|http://en.cppreference.com/w/cpp/string/basic_string/stol^0|I|A|5|7|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]]|E|$]]|$1|F|3|G|5|H|7|10|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|11|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

std::stoi is a <a href="http://en.cppreference.com/w/cpp/string/basic_string/stol" rel="noreferrer" title="std::stol">C++11 function</a>. You have to use the <code>-std=c++11</code> to enable it in both g++ and clang++. This is the actual issue, not a linking error or a specific preprocessor define.

<pre><code> $ cat test.cxx
#include &lt;iostream&gt;
#include &lt;string&gt;

int main()
{
 std::string test = "45";
 int myint = std::stoi(test);
 std::cout &lt;&lt; myint &lt;&lt; '\n';
}
 $ g++ -otest test.cxx
test.cxx: In Funktion »int main()«:
test.cxx:7:17: Fehler: »stoi« ist kein Element von »std«
 int myint = std::stoi(test);
 ^
 $ g++ -otest test.cxx -std=c++11
 $ ./test
45
 $
</code></pre>

edit: I just saw that you used c++11. Are you sure that's making it into your compile options? Check the generated makefile and watch the executed commands to be certain.

blocks|key|1181288|text|使用“set(CMAKE_CXX_STANDARD+11)”表示Cmake|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1181289|entityMap^0|W|5|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|$]]

Use 'set(CMAKE_CXX_STANDARD 11)' for Cmake

My code:

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

int main()
{
 std::string test = "45";
 int myint = std::stoi(test);
 std::cout &lt;&lt; myint &lt;&lt; '\n';
}
</code></pre>

Gives me the compile error:

<pre><code>error: 'stoi' is not a member of 'std'
 int myint = std::stoi(test);
 ^
</code></pre>

However, according to <a href="https://stackoverflow.com/questions/13589947/how-to-use-c11-stdstoi-with-gcc">here</a>, this code should compile fine. I am using the line <code>set(CMAKE_CXX_FLAGS "-std=c++11 -O3")</code> in my <code>CMakeLists.txt</code> file.

Why is it not compiling?

<hr>

Update: I am using <code>gcc</code>, and running <code>gcc --version</code> prints out:

<pre><code>gcc (Ubuntu 5.2.1-22ubuntu2) 5.2.1 20151010
</code></pre>

Compile error: 'stoi' is not a member of 'std'

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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我的代码：#include <iostream>#include <string>int main(){ std::string test = "45"; int myint = std::stoi(test); std::cout << myint << '\n';}给出编译错误：error: 's...

问编译错误：'stoi‘不是'std’的成员
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