The array_udiff Function

The array_udiff function compares arrays and returns elements from the first array that are not present in the subsequent arrays. For element comparison, it uses a callback function that you define yourself. The first parameter is the main array for comparison, the subsequent parameters are arrays to compare against the first one.

Syntax

array_udiff(array1, array2, ..., callback): array;

Example

Let's compare two arrays of numbers using a callback function for comparison:

<?php
	$arr1 = [1, 2, 3, 4, 5];
	$arr2 = [3, 4, 5, 6, 7];
	
	$res = array_udiff($arr1, $arr2, function($a, $b) {
		return $a <=> $b;
	});
	
	print_r($res);
?>

Code execution result:

[1, 2]

Example

Let's compare arrays of strings using a custom comparison function:

<?php
	$arr1 = ['a', 'b', 'c', 'd'];
	$arr2 = ['c', 'd', 'e', 'f'];
	
	$res = array_udiff($arr1, $arr2, function($a, $b) {
		return strcmp($a, $b);
	});
	
	print_r($res);
?>

Code execution result:

['a', 'b']

Example

Comparison with multiple arrays:

<?php
	$arr1 = [1, 2, 3, 4, 5];
	$arr2 = [2, 3, 4];
	$arr3 = [3, 4, 5];
	
	$res = array_udiff($arr1, $arr2, $arr3, function($a, $b) {
		return $a <=> $b;
	});
	
	print_r($res);
?>

Code execution result:

[1]

The array_udiff Function

Syntax

Example

Example

Example

See Also