title: What is the proper use of the comma operator?
body: <p>I saw this code:</p>
  
  <pre><code>if (cond) {
      perror("an error occurred"), exit(1);
  }
  </code></pre>
  
  <p>Why would you do that? Why not just:</p>
  
  <pre><code>if (cond) {
      perror("an error occurred");
      exit(1);
  }
  </code></pre>