array_intersect_key

Definition and usage

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

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

Example

Example 1

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

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

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

Try it yourself

Example 2

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

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

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

Try it yourself

Example 3

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

 <?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 ) ;
?>

Try it yourself

grammar

 array_intersect_key ( array1 , array2 , array3 ... )

illustrate

array_intersect_key() function uses key name comparison to calculate the intersection of an array.

array_intersect_key() returns an array containing the values ​​of all key names that appear in the array being compared and appear in all other parameter arrays at the same time.

Note: Only key names are used for comparison.