title: Why can't I use //-style comments in my C code?
body: <p>I am using <code>gcc</code> (Ubuntu 4.4.1-4ubuntu9) to compile a program that I'm writing, but it seems to vomit whenever it sees a // comment in my code, saying:</p>
  
  <pre><code>interface.c :##: error: expected expression before â/â token&lt;
  </code></pre>
  
  <p>Does the <code>gcc</code> compile mode I'm using forbid <code>//</code> comments?</p>
  
  <pre><code>$ gcc -g -ansi -pedantic interface.c structs.h -c -I. -I/home/me/project/h
  </code></pre>
  
  <p>Why?</p>