title: ctime returning null
body: <p>If the user type <code>time_t</code> is defined as <code>__darwin_time_t</code>, which itself is defined as <code>long</code> in MacOS X, why does the following code outputs <code>8 Time is (null)</code>? Maybe it's something silly, but I can't really understand it.</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;time.h&gt;
  
  int main(void)
  {
      time_t time = 0x7FFFFFFFFFFFFFFF;
  
      printf("%lu\n"
             "Time is %s\n", sizeof(time_t), ctime(&amp;time));
  
      return 0;
  }
  </code></pre>