-1 as a return value
<p>This question is specifically about PHP, but I'm guessing it might be applicable to other languages as well.</p>

<p>I've noticed that between PHP4 and PHP5, the designers of the language shifted away from using <code>-1</code> as a return value to using constants or other forms of output. This makes sense, as <code>-1</code> is not particularly evocative, and I'm guessing this practice led to confusion.</p>

<p>That said, I am sometimes inclined to return <code>-1</code> when I want to quickly add another return option to a function, and <code>-1</code> often seems like a perfectly valid way to express the outcome I am coding for. </p>

<p>So here are my questions:</p>

<ol>
<li><p>Is my observation generally correct, regarding the move away from <code>-1</code> as a return value in PHP5 vs PHP4?</p></li>
<li><p>What are the cons of returning <code>-1</code>, beyond for the reason I mentioned above, wherein the <code>-1</code> return value doesn't contribute positively to code clarity?</p></li>
</ol>
