PHP array_diff_key() function

Example

Compares the keys of two arrays and returns the difference:

<?php$a1=array("a"=>"red","b"=>"green","c"=>"blue");$a2=array("a"=>"red", "c"=>"blue","d"=>"pink");$result=array_diff_key($a1,$a2);print_r($result);?>

Definition and usage

The array_diff_key() function is used to compare the key names of two (or more) arrays and return the difference.

This function compares the keys of two (or more) arrays and returns a difference array that includes all the keys in the compared array ( array1 ) but not in any of the other argument arrays ( array2 or array3, etc.) ) in the key name.

grammar

 array_diff_key( array1,array2,array3... );

parameter	describe
array1	Required. The first array to compare with other arrays.
array2	Required. The array to compare to the first array.
array3,...	Optional. Additional array to compare with the first array.

technical details

Return value:	Returns a difference array containing all keys that are in the compared array ( array1 ) but not in any of the other argument arrays ( array2 or array3 , etc.).
PHP version:	5.1+

More examples

Example 1

Compares the keys of two numeric arrays and returns the difference:

<?php$a1=array("red","green","blue","yellow");$a2=array("red","green","blue");$result=array_diff_key($a1 ,$a2);print_r($result);?>

Example 2

Compare the key names of three arrays and return the difference:

<?php$a1=array("a"=>"red","b"=>"green","c"=>"blue");$a2=array("c"=>"yellow", "d"=>"black","e"=>"brown");$a3 =array("f"=>"green","c"=>"purple","g"=>"red");$result=array_intersect_key($a1,$a2,$a3);print_r($result );?>