usort function in a class

Question

I have a function which sorts data in a multidimensional array, as shown below:

<?php   $data = array();   $data[] = array("name" => "James");   $data[] = array("name" => "andrew");   $data[] = array("name" => "Fred");    function cmp($a, $b)   {       return strcasecmp($a["name"], $b["name"]);   }    usort($data, "cmp");    var_dump($data);   ?>   

When i run this, it works as expected, returning the data ordered by name, ascending. However, I need to use this in a class.

<?php class myClass   {       function getData()       {           // gets all data         $this -> changeOrder($data);     }        function changeOrder(&$data)       {            usort($data, "order_new");     }      function order_new($a, $b)       {           return strcasecmp($a["name"], $b["name"]);       } } ?> 

When I use this, i get the following warning: Warning: usort() expects parameter 2 to be a valid callback, function 'order_new' not found or invalid function name.

When i put the order_new function in the changeOrder function it works fine, but I have problems with Fatal error: Cannot redeclare order_new(), so i cannot use that. Any suggestions?

Answer 1

order_new is a class method not a global function. As the PHP-Manual suggest you can use in this case

usort($data, array($this, "order_new"));  

or declare order_new static and use

usort($data, array("myClass", "order_new"));  

Answer 2

Change to usort($data, array($this, "order_new"));