ksort

(PHP 4, PHP 5, PHP 7, PHP 8)

ksort — Sort an array by key in ascending order

Description

ksort(array &$array, int $flags = SORT_REGULAR): true

Sorts array in place by keys in ascending 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.

Parameters

array

The input array.

flags

The optional second parameter flags may be used to modify the sorting behavior using these values:

Sorting type flags:

Return Values

Always returns true.

Changelog

VersionDescription
8.2.0The return type is true now; previously, it was bool.
8.2.0This function now does numeric string comparison under SORT_REGULAR using the standard PHP 8 rules.

Examples

Example #1 ksort() example

<?php
$fruits = array("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");
ksort($fruits);
foreach ($fruits as $key => $val) {
echo "$key = $val\n";
}
?>

The above example will output:

a = orange
b = banana
c = apple
d = lemon

Example #2 ksort() with int keys

<?php
$a = [0 => 'First', 2 => 'Last', 1 => 'Middle'];
var_dump($a);
ksort($a);
var_dump($a);
?>

The above example will output:

array(3) {
  [0]=>
  string(5) "First"
  [2]=>
  string(4) "Last"
  [1]=>
  string(6) "Middle"
}
array(3) {
  [0]=>
  string(5) "First"
  [1]=>
  string(6) "Middle"
  [2]=>
  string(4) "Last"
}

See Also