Definition and usage of PHP array_diff_key() function

Definition and usage

array_diff_key() function is 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...);

Parameter description:

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.

Return value:

Returns a difference array that includes all elements in the compared array (array1) that are not in any other parameter array (array2) or array3, etc.).

Example display 1:

"red","b"=>"green","c"=>"blue");
$a2=array("a"=>"red","c"=>"blue","d"=>"pink");

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

Run result:

Array ( [b] => green )

Example display 2:

"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);
?>

Run result

Array ( [a] => red [b] => green )

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