title: Determine the size of time_t with preprocessor?
body: <p>Is there a way to know the size of <code>time_t</code> at the time the preprocessor is running?</p>
  
  <p>I'd like to know whether <code>time_t</code> is an <code>int32_t</code> or <code>int64_t</code> and I'd like the trick to work under Linux (POSIX) and Windows (and if possible under Mac OS/X). It'd like it early on so I can do something like this:</p>
  
  <pre><code>#if time_t == _32BIT
  typedef zint32_t my_time_t;
  #else
  typedef zint64_t my_time_t;
  #endif
  </code></pre>
  
  <p>My <code>zint32/64_t</code> types are automatically initialized to zero. That works great for most types, but it is problematic with <code>time_t</code> at this point. Unless I can determine the size at compile time with the preprocessor.</p>