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0

I did look at usort, but am still a little confused...

Here is what the $myobject object looks like:

Array
(
    [0] => stdClass Object
        (
            [tid] => 13
            [vid] => 4
        )

    [1] => stdClass Object
        (
            [tid] => 10
            [vid] => 4
        )

    [2] => stdClass Object
        (
            [tid] => 34
            [vid] => 4
        )

    [3] => stdClass Object
        (
            [tid] => 9
            [vid] => 4
        )

I saw this:

function cmp( $a, $b )
{ 
  if(  $a->weight ==  $b->weight ){ return 0 ; } 
  return ($a->weight < $b->weight) ? -1 : 1;
} 
usort($myobject,'cmp');

I'm trying to sort according to tid, but, I guess I'm just not sure really if I have to change weight to something? Or will it just work as is? I tried it, but nothing outputted...

edited Feb 18 at 8:22

Jon Winstanley
3,188●10●23

asked Feb 18 at 5:52

andy787899
14●2

80% accept rate

John Kugelman · Answer 1 · 2010-02-18 05:57:56Z

2

cmp is the a callback function that usort uses to compare complex objects (like yours) to figure out how to sort them. modify cmp for your use (or rename it to whatever you wish)

function cmp( $a, $b )
{ 
  if(  $a->tid ==  $b->tid ){ return 0 ; } 
  return ($a->tid < $b->tid) ? -1 : 1;
} 
usort($myobject,'cmp');

function sort_by_tid( $a, $b )
{ 
  if(  $a->tid ==  $b->tid ){ return 0 ; } 
  return ($a->tid < $b->tid) ? -1 : 1;
} 
usort($myobject,'sort_by_tid');

http://www.php.net/usort

edited Feb 18 at 5:57

John Kugelman
14.9k●13●41

answered Feb 18 at 5:57

scootklein
51●3

	Ok, thanks for explaining that, but it's still not working... Am I not allowed to assign that to a variable or something? Because when I do $myobject = usort($myobject, 'cmp'), it doesn't output anything at all? I'm assuming I just need one or the other functions from above, and not both, since they both do the same thing? – andy787899 Feb 18 at 6:05
	Also, I did also try renaming the two variables to $myobject1 and $myobject2 = usort... but that didn't work either... – andy787899 Feb 18 at 6:06
	Nevermind! Should have just tried not assigning it before posting... thanks! – andy787899 Feb 18 at 6:09
	usort is one of the few php functions that takes a pointer as an input (very C-ish in style) and returns a boolean. check out the PHP documentation page. try just putting usort($myobject, 'cmp') and then checking what $myobject has. – scootklein Feb 18 at 6:09

Using usort in php to sort an array of objects?

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