array_intersect_assoc

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

array_intersect_assoc — 带索引检查计算数组的交集

说明

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

array_intersect_assoc() 返回一个数组，该数组包含了所有在 array 和其它参数数组中同时存在的值。注意和 array_intersect() 不同的是，键名也用于比较。

参数

array

要检查的数组，作为主值。

arrays

要被对比的数组。

返回值

返回一个关联数组，该数组包含了所有在 array 和其它参数数组中同时存在的值。

范例

Example #1 array_intersect_assoc() 例子

<?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);
?>

以上例程会输出：

Array
(
    [a] => green
)

上面例子中可以看到，只有键值对 "a" => "green" 在两个数组中都存在，从而被返回。 值 "red" 没有被返回，是因为在 $array1 中它的键名是 0 而在 $array2 中 "red" 的键名是 1，键 "b" 没有返回的原因是，它的值和其他数组不同。

仅在 (string) $elem1 === (string) $elem2 时， key => value 才被认为是相等的。 也就是说使用了严格的类型检查，字符串的表达形式必须相同。

参见

User Contributed Notes

Jim Yaghi 23-May-2017 06:25
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.
Whitend 04-Aug-2012 08:08
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.
StR: str at strgt dot cjb dot net 13-Oct-2005 05:34
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;
}
?>
vandor at progressive dot hu 14-Dec-2004 11:26
# 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
)
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