array_intersect_assoc

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

array_intersect_assoc — Computes 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.

Changelog

Version	Description
8.0.0	This function can now be called with only one parameter. Formerly, at least two parameters have been required.

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.

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User Contributed Notes 4 notes

down

Whitend ¶

11 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.

down

vandor at progressive dot hu ¶

19 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
)

down

-6

Jim Yaghi ¶

7 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.

down

-7

StR: str at strgt dot cjb dot net ¶

18 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;
}
?>

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array_intersect_assoc

Description

Parameters

Return Values

Changelog

Examples

See Also

Improve This Page

User Contributed Notes 4 notes