PHP array_diff_uassoc() Function

Last Updated : 17 Mar 2025

This function is inbuilt in PHP and it was introduced in PHP 5. The function array_diff_uassoc() is used to compute the difference of arrays with additional index check which is performed by a user supplied callback function.

In simple words, the function compares array1 against array2 and returns the difference.

Syntax

Parameter	Description	Is compulsory
array1	The array to compare from	compulsory
array2	An array to compare against	compulsory
array3	More arrays to compare against	Optional
User defined function	The specified callback function. The function returns an integer less than, equal to or greater than zero.	compulsory

Important note: This function uses a user-defined function to compare the keys.

Return Type

This function returns an array containing the entries from array1 that are not present in any of the other ways.

Example 1

Output:

Array(  [10] => sid [20] => raj )

Example 2

Output:

Array ( [b] => brown [c] => blue [0] => red )

Example 3

Output:

Array (  [c] => orange )

Example 4

Output:

Array (  [b] => brown [c] => blue [0] => red )