title: Why use !! when converting int to bool?
body: <p>What can be a reason for converting an integer to a boolean in this way?</p>
  
  <pre><code>bool booleanValue = !!integerValue;
  </code></pre>
  
  <p>instead of just</p>
  
  <pre><code>bool booleanValue = integerValue;
  </code></pre>
  
  <p>All I know is that in VC++7 the latter will cause <a href="http://msdn.microsoft.com/en-us/library/b6801kcy(VS.71).aspx" rel="noreferrer">C4800 warning </a> and the former will not. Is there any other difference between the two?</p>