UASORT(3) 1 UASORT(3)
uasort - Sort an array with a user-defined comparison function and maintain index association
SYNOPSIS
bool uasort (array &$array, callable $value_compare_func)
DESCRIPTION
This function sorts an array such that array indices maintain their correlation with the array elements they are associated with, using a
user-defined comparison function.
This is used mainly when sorting associative arrays where the actual element order is significant.
Note
If two members compare as equal, their relative order in the sorted array is undefined.
PARAMETERS
o $array
- The input array.
o $value_compare_func
- See usort(3) and uksort(3) for examples of user-defined comparison functions.
RETURN VALUES
Returns TRUE on success or FALSE on failure.
EXAMPLES
Example #1
Basic uasort(3) example
<?php
// Comparison function
function cmp($a, $b) {
if ($a == $b) {
return 0;
}
return ($a < $b) ? -1 : 1;
}
// Array to be sorted
$array = array('a' => 4, 'b' => 8, 'c' => -1, 'd' => -9, 'e' => 2, 'f' => 5, 'g' => 3, 'h' => -4);
print_r($array);
// Sort and print the resulting array
uasort($array, 'cmp');
print_r($array);
?>
The above example will output:
Array
(
[a] => 4
[b] => 8
[c] => -1
[d] => -9
[e] => 2
[f] => 5
[g] => 3
[h] => -4
)
Array
(
[d] => -9
[h] => -4
[c] => -1
[e] => 2
[g] => 3
[a] => 4
[f] => 5
[b] => 8
)
SEE ALSO
usort(3), The comparison of array sorting functions.
PHP Documentation Group UASORT(3)
