What are ticks used for in PHP?
<p>I'd like to know why, how and when to use ticks in PHP:</p>

<pre><code>declare(ticks=1);

// A function called on each tick event
function tick_handler()
{
    echo "tick_handler() called\n";
}

register_tick_function('tick_handler');

$a = 1;

if ($a &gt; 0) {
    $a += 2;
    print($a);
}
</code></pre>
