How to sort an array based on a specific field in the array?

How can I sort an array based on two specific values within the array? For instance:

$arr = array(
             array('a' => array('field1' => 'Abc', 'field2' => 'Def'), 'b' => 0)
             array('a' => array('field1' => 'Ghi', 'field2' => 'Jkl'), 'b' => 0)
            );

I want to 开发者_开发技巧sort this array based on the $arr[$i]['a']['field1'] variable. How can I do that?

Give this a try:

function cmp($a, $b) {
    if ($a['a']['field1'] == $b['a']['field1'] )
        return 0;
    return ( $a['a']['field1'] < $b['a']['field1'] ) ? -1 : 1;
}

uasort($arr, 'cmp');

This is just a slight alteration of the example provided on the PHP documentation page: http://www.php.net/manual/en/function.uasort.php

Create your own comparison function and use uasort

http://us.php.net/manual/en/function.uasort.php

in this particular case (sort on very first item of the very first subarray), simple sort() will be enough.