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array_intersect_assoc

(PHP 4 >= 4.3.0, PHP 5, PHP 7)

array_intersect_assocComputes the intersection of arrays with additional index check

Description

array_intersect_assoc ( array $array , array ...$arrays ) : array

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

Parameters

array

The array with master values to check.

arrays

Arrays to compare values against.

Return Values

Returns an associative array containing all the values in array 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

  • array_intersect() - Computes the intersection of arrays
  • array_uintersect_assoc() - Computes the intersection of arrays with additional index check, compares data by a callback function
  • array_intersect_uassoc() - Computes the intersection of arrays with additional index check, compares indexes by a callback function
  • array_uintersect_uassoc() - Computes the intersection of arrays with additional index check, compares data and indexes by separate callback functions
  • array_diff() - Computes the difference of arrays
  • array_diff_assoc() - Computes the difference of arrays with additional index check
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User Contributed Notes 4 notes

up
4
Whitend
8 years 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
4
vandor at progressive dot hu
15 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
)
up
-6
StR: str at strgt dot cjb dot net
15 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
-6
Jim Yaghi
3 years ago
Remember, null values will be interpreted as, "key does not exist." eg,

$a = ['apples' => 1, 'oranges' => 2, 'turtles' => null, 'bananas'=>4];
$b = ['apples'=>10, 'turtles' => 11, 'eggs'=>12];
$c = array_intersect_assoc($b,$a);

You might have expected $c to contain:

['oranges' => 10, 'turtles' => 11]

In fact, 'turtles' has a null value in the $a array, therefore the $c array contains only:

['oranges' => 10]

Something to keep in mind if using array_intersect_assoc to filter valid entries, eg in a mySQL insertion pre-processing or nerdy API that doesn't like extra params.
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