array_intersect_assoc

(PHP 4 >= 4.3.0, PHP 5)

array_intersect_assocComputes the intersection of arrays with additional index check

Description

array array_intersect_assoc ( array $array1 , array $array2 [, array $... ] )

array_intersect_assoc() returns an array containing all the values of array1 that are present in all the arguments. Note that the keys are used in the comparison unlike in array_intersect().

Parameters

array1

The array with master values to check.

array2

An array to compare values against.

...

A variable list of arrays to compare.

Return Values

Returns an associative array containing all the values in array1 that are present in all of the arguments.

Examples

Example #1 array_intersect_assoc() example

<?php
$array1 
= array("a" => "green""b" => "brown""c" => "blue""red");
$array2 = array("a" => "green""b" => "yellow""blue""red");
$result_array array_intersect_assoc($array1$array2);
print_r($result_array);
?>

The above example will output:

Array
(
    [a] => green
)

In our example you see that only the pair "a" => "green" is present in both arrays and thus is returned. The value "red" is not returned because in $array1 its key is 0 while the key of "red" in $array2 is 1, and the key "b" is not returned because its values are different in each array.

The two values from the key => value pairs are considered equal only if (string) $elem1 === (string) $elem2 . In other words a strict type check is executed so the string representation must be the same.

See Also

add a note add a note

User Contributed Notes 3 notes

up
2
Whitend
1 year ago
One of the ways to get intersection of two arrays is as follows:

<?php
function arrayIntersect( $primary_array, $secondary_array ) {
   
    if ( !
is_array( $primary_array ) || !is_array( $secondary_array ) ) {
        return
false;
    }
   
    if ( !empty(
$primary_array ) ) {
       
        foreach(
$primary_array as $key => $value ) {
           
            if ( !isset(
$secondary_array[$key] ) ) {
                unset(
$primary_array[$key] );
            } else {
                if (
serialize( $secondary_array[$key] ) != serialize( $value ) ) {
                    unset(
$primary_array[$key] );
                }
            }
           
        }
       
        return
$primary_array;
       
    } else {
        return array();
    }
   
}
?>

It would pay attention to both keys and values even if values would be arrays as well. One important note is that if value of $primary_array is yet another array, its order of key & value pairs becomes important for matching.
up
2
StR: str at strgt dot cjb dot net
8 years ago
To find the keys that are in 2 arrays, without caring of the values:

This is a function i needed, and it also returns the values of the first array

<?php
function array_key_intersect(&$a, &$b) {
 
$array = array();
  while (list(
$key,$value) = each($a)) {
    if (isset(
$b[$key]))
     
$array[$key] = $value;
  }
  return
$array;
}
?>
up
0
vandor at progressive dot hu
9 years ago
# ket tomb kulcs alapu metszetet szamitja ki, az erteken is ellenorzest vegez
#
# calculating (key base) intersection of arrays (value are checked)
# use: $result_array = array_intersect_assoc($a1, $a2, $a3,..);
#
##
# original code by [jochem at iamjochem dawt com] : array_diff_keys()

<?php
function array_intersect_assoc() {

   
$args = func_get_args();
   
$res = $args[0];

    for (
$i=1;$i<count($args);$i++) {
        if (!
is_array($args[$i])) {continue;}

        foreach (
$res as $key => $data) {
            if ( (!
array_key_exists($key, $args[$i])) || ( (isset($args[$i][$key])) && ($args[$i][$key] !== $res[$key]) ) ) {
                unset(
$res[$key]);
            }
        }
    }

    return
$res;
}

?>

<?php
$array1
= array("a"=>"green", "b"=>"brown", "c"=>"blue", "red");
$array2 = array("a"=>"green", "b"=>"yellow", "c"=>"yellow", "red");
$a = array('a'=>'green', 'b'=>'brown', 'c'=>'yellow');
$b = array('a'=>'green', 'b'=>'brown', 'c'=>'yellow', 'e'=>'yellow');

$result_array = array_intersect_assoc($a, $b, $array1, $array2);
?>

$args array will look like:

(
    0 =>
        (
            a => green
            b => brown
            c => yellow
        )

    1 =>
        (
            a => green
            b => brown
            c => yellow
            e => yellow
        )

    2 =>
        (
            a => green
            b => brown
            c => blue
            0 => red
        )

    3 =>
        (
            a => green
            b => yellow
            c => yellow
            0 => red
        )

)

$result_array will look like:

(
    a => green
)
To Top