PHP array_diff_key() Function

Example

Compare the keys of two arrays, and return the differences:

<?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);
?>

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Definition and Usage

The array_diff_key() function compares the keys of two (or more) arrays, and returns the differences.

This function compares the keys of two (or more) arrays, and return an array that contains the entries from array1 that are not present in array2 or array3, etc.

Syntax

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

Parameter Values

Parameter	Description
array1	Required. The array to compare from
array2	Required. An array to compare against
array3,...	Optional. More arrays to compare against

Technical Details

Return Value:	Returns an array containing the entries from array1 that are not present in any of the other arrays
PHP Version:	5.1+

More Examples

Example

Compare the keys of two indexed arrays, and return the differences:

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

$result=array_diff_key($a1,$a2);
print_r($result);
?>

Try it Yourself »

Example

Compare the keys of three arrays, and return the differences:

<?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");

$result=array_diff_key($a1,$a2,$a3);
print_r($result);
?>

Try it Yourself »

❮ PHP Array Reference