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"));