title: Why does return 0 or break not work with the comma operator?
body: <p>I can write the code <code>if(1) x++, y++;</code> instead of <code>if(1) {x++; y++;}</code>, but in some cases it does not work (see below). It would be nice if you tell me about this.</p>
  
  <pre><code>int x = 5, y = 10;    
  if (x == 5) x++, y++;  // It works
  
  if (x == 5) x++, return 0; // It shows an error
  </code></pre>
  
  <p>The same applies to <code>for</code> loops:</p>
  
  <pre><code>for (int i = 0; i &lt; 1; i++) y++, y += 5; // It works
  
  for (int i = 0; i &lt; 1; i++) y++, break; // Does not work
  </code></pre>