Question

alright, I’m trying something which should be like really easy.

Here it is:

usort($newarr, "cmp");

function cmp($a, $b)
{ return 0; }

The problem is simple: it does not sort the array by giving this warning message

Warning: usort() expects parameter 2 to be a valid callback, function 'cmp' not found or invalid function name

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I have read this answer here PHP usort won't sort

but it just doesn’t make any sense to me, I do not have a class like how it is explained in the answer 1 (and I don’t even need any, i tried with $this, this, insted of “myclass” but it’s simply not working any):

usort($items, array("MyClass", "compare_method"));

Answer 1

Change the script flow, by the time you are trying to sort your array cmp does not exists yet. So, this should work:

function cmp($a, $b)
{ return 0; }

usort($newarr, "cmp");