The array_diff_ukey Function

The array_diff_ukey function compares the keys of several arrays and returns elements from the first array whose keys are absent in the other arrays. A user-defined callback function is used to compare the keys. The first parameter is the main array, the subsequent parameters are arrays for comparison, and the last parameter is the callback function.

Syntax

array_diff_ukey(array $array1, array $array2 [, array $... ], callable $key_compare_func): array

Example

Let's compare two arrays by keys using the strcasecmp callback function (case-insensitive comparison):

<?php
	$array1 = ['A' => 1, 'b' => 2, 'C' => 3];
	$array2 = ['a' => 4, 'B' => 5];
	
	$res = array_diff_ukey($array1, $array2, 'strcasecmp');
	print_r($res);
?>

Code execution result:

['C' => 3]

Example

Let's compare three arrays with a custom callback function:

<?php
	function keyCompare($key1, $key2) {
		return $key1 <=> $key2;
	}

	$array1 = [1 => 'a', 2 => 'b', 3 => 'c'];
	$array2 = [1 => 'd', 4 => 'e'];
	$array3 = [2 => 'f'];
	
	$res = array_diff_ukey($array1, $array2, $array3, 'keyCompare');
	print_r($res);
?>

Code execution result:

[3 => 'c']

The array_diff_ukey Function

Syntax

Example

Example

See Also