title: popen on c++11 not found
body: <p>I am trying to run gnuplot from a c++ program in a portable fashion. Ironically enough for WIN_32 I have no problem, but my compiler (visual studio 2015)can't identify the POSIX command popen() that I am trying to use for other OS. Is popen() nonexistent in C++11, is there an equivalent or must I change standards?</p>
  
  <p>this compiles and runs in windows visual studio 2015 :</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  
  int main()
  {
    _popen(" ", "w");
    return 0;
  }
  </code></pre>
  
  <p>this does not compile :</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  
  int main()
  {
    popen(" ", "w");
    return 0;
  }
  </code></pre>
  
  <p>error 
  Error   C3861   'popen': identifier not found<br>
  at the end of the day, I want a behavior like</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  
  int main()
  {
    #ifdef WIN_32
      _popen(" ", "w");
    #else
      popen(" ", "w");
    #endif
    return 0;
  }
  </code></pre>
  
  <p>I expect this program to be recompiled in g++ when used on Linux and Mac, but I would like to use msvc14 to compile on windows</p>