title: In the main function of a C++ program, what does `return 0` do and mean?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/4207134/what-is-the-proper-declaration-of-main">What is the proper declaration of main?</a>  </p>
  </blockquote>
  
  
  
  <p>Without citing any code in particular, I am looking for an explanation of the below example:</p>
  
  <pre><code>#include &lt;iostream&gt;
  
  int main()
  {
      std::cout &lt;&lt; "Hello world" &lt;&lt; std::endl;
      return 0;
  }
  </code></pre>
  
  <p>I don't understand what <code>return 0</code> does. Can you please explain this in as plain English as possible?</p>