title: What does #pragma once mean in C?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/1263521/pragma-help-understanding">#pragma - help understanding</a>  </p>
  </blockquote>
  
  
  
  <p>I saw the <code>pragma</code> many times,but always confused, anyone knows what it does?Is it windows only?</p>