title: Simple _putenv example not working
body: <p>I tried using getenv and setenv under cl.exe under Visual Studio 2008.
  getenv worked but setenv didn't. After some browsing I found out that _putenv is an alternative.</p>
  
  <p>The following snippet didn't work</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  
  int main()
  {
     _putenv("Hello=123");
  }
  
  C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC&gt;putenv.exe
  
  C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC&gt;echo %Hello%
  %Hello%
  </code></pre>
  
  <p>What could be the reason?</p>