title: Abnormal Behavior of the function "localtime" in C
body: <p>I used the function <code>localtime</code> twice by putting in the same argument.
  However, I may get different results. The latter one may have one second more. The code is below.</p>
  
  <pre><code>ptCurrentTime = localtime(&amp;(t_TriggerTime));
  ptCurrentTime = localtime(&amp;(t_TriggerTime));
  </code></pre>
  
  <p>I printed out the results. The first one may be like <code>2015-11-07 22:19:56.123</code> and the second one may be like <code>2015-11-07 22:19:57.123</code>.
  Is that normal?</p>