Multidimension Array Sort

[ripper2020]

Hello all I am pretty new to php and am working on a page with some order statistics. My current array has all the data I need and is as follows:
if($unique[$x] != NULL){
$db_loco[$x]['city']= $unique[$x];
$db_loco[$x]['orders'] = $orders;
$db_loco[$x]['state'] = $db_res[$x]['vSState'];}
}

So I end up with city state and number of orders all with the same index. The problem is the user needs to be able to sort this array by order number, city, or state. I have no clue how to do this or if it is even possible with this array, if there is a better way of making the array please let me know, I was looking into array_multisort but couldn't figure out how to do it. Any help would be much appreciated thanx.

[NogDog]

You can use usort() (http://www.php.net/usort). For example, to sort by city:

function cmp($a, $b)
{
return strcmp($a["city"], $b["city"]);
}
usort($db_loco, "cmp");

[ripper2020]

Thanx, could you explain a little bit about what this function does because I don't understand what its doing...for the most part it worked except the first 2 elements in the array are wrong...for example
IA Belle Plaine 1
NY springfield gardens 1
Other AGEGE ***** 1
MD ANNAPOLIS 1
After the first two it sppears they are in alphabetical order...if I knew more about what this function was doing i could try and fix...or do you know why it would be doing this?

[NogDog]

Could be a couple things (at least 2 that occur to me, anyway): it could be an upper-/lower-case sorting problem, and there could be leading white-space throwing off the comparison. See if this is any better:

function cmp($a, $b)
{
return strcasecmp(trim($a["city"]), trim($b["city"]));
}
usort($db_loco, "cmp");

[ShrineDesigns]

use strnatcmp() in place of strcmp()

[NogDog]

use strnatcmp() in place of strcmp()
Or strnatcasecmp() (http://www.php.net/strnatcasecmp) :)

[ripper2020]

the sorting for order totals works ascending( i think) that is it goes from least to greatest using the sort command...how do i make it do the opposite...greatest to least??

[ShrineDesigns]

the reversal function for usort() is ursort()