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# array_intersect_ukey

(PHP 5 >= 5.1.0RC1)

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

## Description

array array_intersect_ukey ( array array1, array array2 [, array ..., callback key_compare_func] )

array_intersect_ukey() returns an array containing all the values of `array1` which have matching keys that are present in all the arguments.

This comparison is done by a user supplied callback function. It must return an integer less than, equal to, or greater than zero if the first key is considered to be respectively less than, equal to, or greater than the second.

Example 1. array_intersect_ukey() example

`<?php function key_compare_func($key1, $key2) { if ($key1 == $key2) return 0; else if ($key1 > $key2) return 1; else return -1; } $array1 = array('blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4); $array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan' => 8); var_dump(array_intersect_ukey($array1, $array2, 'key_compare_func')); ?>`

The above example will output:

    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 `array1`.

See also array_diff(), array_udiff() array_diff_assoc(), array_diff_uassoc(), array_udiff_assoc(), array_udiff_uassoc(), array_diff_key(), array_diff_ukey(), array_intersect(), array_intersect_assoc(), array_intersect_uassoc() and array_intersect_key().

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