sorting a multidimensional array

[prock]

the next time someone looks at you and says, "I'm going to build an application that uses all flat files instead of a database!"

SMACK HIM! SMACK ME!

Ok, so I've got a multidim array that I've read up from a pipe delimed file:

main_array
(
[0] => array
(
[0] => 1 //record id
[1] => 010203 //date [mmddyy]
[2] => a string //a string
)
[1] => array
(
[0] => 1 //record id
[1] => 010103 //date [mmddyy]
[2] => a string //a string
)

Any idea how I would sort this so that its $main_array is re-ordered by date? I'm sure this question has been asked before but I can't really find it. array_multisort in the manual claims to work but not really the way I want.

[ahundiak]

What you probably need to do is to use usort() and make your own compare function. It's easy. Check the manual for details.

[prock]

function cmp ($a, $b)
{
if ($a['1'] == $b['1']) return 0;
return ($a['1'] > $b['1']) ? -1 : 1;
}

usort($dbdata,'cmp');
print_r($dbdata);

Ok, I just basically cribbed this elsewhere. And it works. Can someone please explain why? I mean what exactly is going on?