title: C Preprocessor testing definedness of multiple macros
body: <p>I searched the site but did not find the answer I was looking for so here is a really quick question.</p>
  
  <p>I am trying to do something like that :</p>
  
  <pre><code>#ifdef _WIN32 || _WIN64
       #include &lt;conio.h&gt;
  #endif
  </code></pre>
  
  <p>How can I do such a thing? I know that _WIN32 is defined for both 32 and 64 bit windows so I would be okay with either for windows detection. I am more interested in whether I can use logical operators like that with preprocessor directives, and if yes how, since the above does not work.</p>
  
  <p>Compiling with gcc I get :</p>
  
  <blockquote>
    <p>warning: extra tokens at end of #ifdef directive , and it basically just takes the first MACRO and ignores the rest.</p>
  </blockquote>