(PHP 5 >= 5.1.0, PHP 7, PHP 8)

array_intersect_ukey — Computes the intersection of arrays using a callback function on the keys for comparison

Description

Parameters

array

Initial array for comparison of the arrays.

arrays

Arrays to compare keys against.

key_compare_func

The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.

Caution

Returning non-integer values from the comparison function, such as float, will result in an internal cast to int of the callback's return value. So values such as 0.99 and 0.1 will both be cast to an integer value of 0, which will compare such values as equal.

Return Values

Returns the values of array whose keys exist in all the arguments.

Examples

array(2) {
  ["blue"]=>
  int(1)
  ["green"]=>
  int(3)
}

In our example you see that only the keys 'blue' and 'green' are present in both arrays and thus returned. Also notice that the values for the keys 'blue' and 'green' differ between the two arrays. A match still occurs because only the keys are checked. The values returned are those of array.

See Also

• array_diff() - Computes the difference of arrays
• array_udiff() - Computes the difference of arrays by using a callback function for data comparison
• array_diff_assoc() - Computes the difference of arrays with additional index check
• array_diff_uassoc() - Computes the difference of arrays with additional index check which is performed by a user supplied callback function
• array_udiff_assoc() - Computes the difference of arrays with additional index check, compares data by a callback function
• array_udiff_uassoc() - Computes the difference of arrays with additional index check, compares data and indexes by a callback function
• array_diff_key() - Computes the difference of arrays using keys for comparison
• array_diff_ukey() - Computes the difference of arrays using a callback function on the keys for comparison
• array_intersect() - Computes the intersection of arrays
• array_intersect_assoc() - Computes the intersection of arrays with additional index check
• array_intersect_uassoc() - Computes the intersection of arrays with additional index check, compares indexes by a callback function
• array_intersect_key() - Computes the intersection of arrays using keys for comparison

"array_intersect_ukey" will not work if $key_compare_func is using regular expression to perform comparison. "_array_intersect_ukey" fully implements the "array_intersect_ukey" interface and handles properly boolean comparison. However, the native implementation should be preferred for efficiency reasons.

<?php
$key_compare_func = function ($a, $b) {
    var_dump('a=' . $a. '; b=' . $b);
    
    if (strpos($b, '/') === 0) {
        return preg_match($b, $a) > 0 ? 0 : -1;
    }
    
    if ($a == $b) {
        $weight = 0;
    } else if ($a > $b) {
        $weight = 1;
    } else {
        $weight = -1;
    }
    
    var_dump('literal comparison: ' . $weight);
    
    return $weight;
};

$foo = ['aab' => '', 'bbb' => '', 'ccb' => '', 'abb' => ''];
$bar = ['/[a-z]b[a-z]/' => ''];
$buz = ['/c[a-z][a-z]/' => ''];

echo PHP_EOL . 'array_intersect_ukey' . PHP_EOL . PHP_EOL;

$subject = array_intersect_ukey ($foo, $bar, $buz, $key_compare_func);

echo PHP_EOL;

var_dump($subject);

echo PHP_EOL . '_array_intersect_ukey' . PHP_EOL . PHP_EOL;

$subject = _array_intersect_ukey($foo, $bar, $buz, $key_compare_func);

echo PHP_EOL;

var_dump($subject);

/**
 * @author Gajus Kuizinas <gk@anuary.com>
 * @version 1.0.0 (2013 09 30)
 * @url https://gist.github.com/gajus/271ad5f36337a32a184c
 */
function _array_intersect_ukey (array $arr1, array $arr2, $key_compare_func) {
    $arr_matched = [];
    $arr_unmatched = [];
    
    $args = func_get_args();
    
    $key_compare_func = end($args);
    
    foreach ($arr1 as $k1 => $v1) {
        foreach ($arr2 as $k2 => $v2) {
            $diff = $key_compare_func($k1, $k2);
        
            //var_dump('k1=' . $k1 . ', k2=' . $k2 . ', diff=' . $diff);
            
            if ($diff === 0) {
                $arr_matched[$k1] = $v1;
            } else {
                $arr_unmatched[$k1] = $v1;
            }
        }
    }
    
    if (count($args) <= 3) {
        return $arr_matched;
    }
    
    array_splice($args, 0, 2, [$arr_unmatched]);
    
    return array_merge($arr_matched, call_user_func_array('_array_intersect_ukey', $args));
}

/*
array_intersect_ukey

string(12) "a=bbb; b=aab"
string(21) "literal comparison: 1"
string(12) "a=bbb; b=ccb"
string(22) "literal comparison: -1"
string(12) "a=abb; b=bbb"
string(22) "literal comparison: -1"
string(12) "a=aab; b=abb"
string(22) "literal comparison: -1"
string(22) "a=aab; b=/[a-z]b[a-z]/"
string(22) "a=abb; b=/[a-z]b[a-z]/"
string(22) "a=abb; b=/c[a-z][a-z]/"

array(0) {
}

_array_intersect_ukey

string(22) "a=aab; b=/[a-z]b[a-z]/"
string(22) "a=bbb; b=/[a-z]b[a-z]/"
string(22) "a=ccb; b=/[a-z]b[a-z]/"
string(22) "a=abb; b=/[a-z]b[a-z]/"
string(22) "a=aab; b=/c[a-z][a-z]/"
string(22) "a=ccb; b=/c[a-z][a-z]/"

array(3) {
  ["bbb"]=>
  string(0) ""
  ["abb"]=>
  string(0) ""
  ["ccb"]=>
  string(0) ""
}*/
?>