title: How do I check if one of multiple macros is defined in a single #ifdef?
body: <p>I have some C++ code, and want to perform an action if the <code>__APPLE__</code> or <code>__linux</code> macros are defined.</p>
  
  <p>If I did it as a normal <code>if</code> conditional, it would be easy using <code>||</code>:</p>
  
  <pre><code>if (something || something) { .. code .. }
  </code></pre>
  
  <p>But as of what I know there is no <code>||</code> operator for <code>#ifdef</code> statements. How would I check if <code>__APPLE__</code> or <code>__linux</code> is defined using a single <code>#ifdef</code> statement?</p>