title: C++ Determining if a variable is set
body: <p>I have a variable that is defined:</p>
  
  <pre><code>SYSTEMTIME m_TOTime;
  </code></pre>
  
  <p>And I call GetSystemTime Function to get the UTC Time:</p>
  
  <pre><code>GetSystemTime( &amp;m_TOTime );
  </code></pre>
  
  <p>Is it possible to determine if GetSystemTime has been called to set m_TOTime? I have another function that uses this variable, but if GetSystemTime has not been called (which sometimes it doesnt have to be) it returns a blank object. I was hopeing something like m_TOTime == null would work.</p>