Callback function in array_filter
<p>I'm trying to delete empty elements in an array with the function array_filter.</p>

<p>When i use an external callback like this :</p>

<pre><code>function callback($a) { return !empty($a);}
$arr = array("abc",'','ghi');
$res = array_filter($arr, "callback");
</code></pre>

<p>it works as expected.</p>

<p>But if i use array_filter like that :</p>

<pre><code>$arr = array("abc",'','ghi');
$res = array_filter($arr, function($a) { return !empty($a);});
</code></pre>

<p>It fails with the error :</p>

<pre><code>PHP Parse error:  syntax error, unexpected T_FUNCTION in test.php on line 2
</code></pre>

<p>What am i doing wrong ?</p>
