Calling comparison functions that are defined within classes?

[Kadence]

I'd like to call a comparison function that's defined within a class in static fashion, in PHP4. Example code:

$array = array(100, 40, 120, 125, 110, 60);
usort($array, Test::cmp_function);
//$test = new Test();
//usort($array, $test->cmp_function);
print_r($array);

class Test {
	function cmp_function($a, $b) {
		return ($a>$b);
	}
}

Trying to call the function with Test::cmp_function however gives the error Parse error: syntax error, unexpected ')', expecting '('. And commenting that line out and uncommenting the object-oriented lines gives the warning Warning: usort() [function.usort]: Invalid comparison function.

How can I call the Test::cmp_function comparison function?

[Jake Arkinstall]

A callback can either be a string containing the function name, or an array - the first item being the class/object, the second being the method.

usort($array, array($test, 'cmp_function')); 

[Kadence]

Thank you very much, that works