PHP function array_diff_key() used to compare the key names of two arrays and return the difference

Example

Compare the key names of two arrays and return the difference set:

<?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

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

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

Syntax

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

Technical details

More examples

Example 1

Compare the key names of two numerical arrays and return the difference set:

<?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 set:

<?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);
?>

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