Difference between array_map, array_walk and array_filter
<p>What exactly is the the difference between <code>array_map</code>, <code>array_walk</code> and <code>array_filter</code>. What I could see from documentation is that you could pass a callback function to perform an action on the supplied array. But I don't seem to find any particular difference between them.</p>

<p>Do they perform the same thing?<br>
Can they be used interchangeably?</p>

<p>I would appreciate your help with illustrative example if they are different at all.</p>

<p>Thanks</p>
