title: Where is WIN32 defined, and how can I include this definition in my project?
body: <p>I am including a third party header and source file into my project. </p>
  
  <p>At the top of the header there is this:</p>
  
  <pre><code>#if defined(WIN32) || defined(WIN16)
  #ifndef MSDOS
  #define MSDOS
  #endif
  #endif
  
  #include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  #ifndef MSDOS
  #include &lt;unistd.h&gt;
  #endif
  #include "des.h"
  </code></pre>
  
  <p>The problem is that #if defined(WIN32) fails and the compilation fails when trying to #include unistd.h which I don't want to do.</p>
  
  <p>I have third party project that works with this header file i.e. WIN32 is defined and it doesn't try to include  In Visual Studio I did "Go To Definition" on "WIN32" and was taken to the following definition in WinDefs.h.</p>
  
  <pre><code>#define WIN32
  </code></pre>
  
  <p>I'm not sure this is where its getting WIN32 definition from, as the third party project does not appear to include "WinDefs.h".</p>
  
  <p>So my problem is, how can I get WIN32 to be defined in my current new project?</p>