PHP usort() Function
Example
Sort the elements of an array by values using a user-defined comparison function:
<?php
function my_sort($a, $b) {
if ($a == $b) return 0;
return ($a < $b) ? -1 : 1;
}
$a = array(4, 2, 8, 6);
usort($a, "my_sort");
foreach($a as $key => $value) {
echo "[" . $key . "] => " .
$value;
echo "<br>";
}
?>
Try it Yourself »
Definition and Usage
The usort() function sorts an array by values using a user-defined comparison function.
Tip: Use the uksort() function to sort an array by keys using a user-defined comparison function.
Tip: Use the uasort() function to sort an array by values (and maintain the index association) using a user-defined comparison function.
Syntax
usort(array, callback)
Parameter Values
| Parameter | Description |
|---|---|
| array | Required. Specifies the array to sort |
| callback | Required. A comparison function. Must return an integer <, =, or > than 0 if the first argument is <, =, or > than the second argument |
Technical Details
| Return Value: | Always returns TRUE |
|---|---|
| PHP Version: | 4+ |
| PHP Changelog: | PHP 8.2.0: Now returns TRUE (previously it returned bool) PHP 8.0.0: If callback expects a parameter to be passed by reference, it will now return an E_WARNING |
❮ PHP Array Reference
