title: Can I conditionally check the value of a macro using the C preprocessor?
body: <p>I know I can use the C preprocessor to conditionally compile something like:</p>
  
  <pre><code>#define USESPECIALFEATURE
  
  #if defined USESPECIALFEATURE
  usespecialfeature();
  #endif
  </code></pre>
  
  <p>But I am wondering if I can do something like this:</p>
  
  <pre><code>#define USEDFEATURE 4
  
  #if defined USEDFEATURE == 4
  usefeature(4);
  #endif
  </code></pre>
  
  <p>In other words, I want to use the preprocessor to check the value of a particular macro definition. This doesn't work when I tried it.</p>