(PHP 4, PHP 5, PHP 7, PHP 8)
uksort — Sort an array by keys using a user-defined comparison function
Sorts array in place by keys using a
user-supplied comparison function to determine the order.
Note:
If two members compare as equal, they retain their original order. Prior to PHP 8.0.0, their relative order in the sorted array was undefined.
Note:
Resets array's internal pointer to the first element.
arrayThe input array.
callbackThe comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.
Returning non-integer values from the comparison
function, such as float, will result in an internal cast to
int of the callback's return value. So values such as
0.99 and 0.1 will both be cast to an
integer value of 0, which will compare such values as equal.
Always returns true.
| Version | Description |
|---|---|
| 8.2.0 |
The return type is true now; previously, it was bool.
|
| 8.0.0 |
If callback expects a parameter to be passed
by reference, this function will now emit an E_WARNING.
|
Example #1 uksort() example
<?php
function cmp($a, $b)
{
$a = preg_replace('@^(a|an|the) @', '', $a);
$b = preg_replace('@^(a|an|the) @', '', $b);
return strcasecmp($a, $b);
}
$a = array("John" => 1, "the Earth" => 2, "an apple" => 3, "a banana" => 4);
uksort($a, "cmp");
foreach ($a as $key => $value) {
echo "$key: $value\n";
}
?>
The above example will output:
an apple: 3 a banana: 4 the Earth: 2 John: 1