PHP compares the key names of two arrays and returns the intersection function array_intersect_key()

Example

Compare the key names of two arrays and return the intersection:

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

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

Definition and usage

array_intersect_key() Function is used to compare the key names of two (or more) arrays and return the intersection.

This function compares the key names of two (or more) arrays and returns an intersection array that includes everything in the compared array (array1) and any other parameter arrays. (array2 or array3, etc.).

Syntax

array_intersect_key(array1,array2,array3...)

Parameters	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.

Technical details

Return value:	Returns an intersection array, which contains All keys in the compared array (array1) that are also in any other parameter arrays (array2 or array3, etc.).
PHP version:	5.1.0+

More examples

Examples 1

Compare the key names of two numerical arrays and return the intersection:

Example 2

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

"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);
?>

Instance:

  1 ,  'two'   =>  2 ,  'three'   =>  3 ,  'five'  =>  4 ); 
$array2  = array( 'six'  =>  5 ,  'one'  =>  6 ,  'five'  =>  7 ,  'ten'    =>  8 );
 var_dump ( array_intersect_key ( $array1 ,  $array2 ));
?>

Run result:

array(2) { ["one"]=> int(1) ["five"]=> int(4) }

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