php man page for array_intersect_key

ARRAY_INTERSECT_KEY(3)							 1						    ARRAY_INTERSECT_KEY(3)

array_intersect_key - Computes the intersection of arrays using keys for comparison

SYNOPSIS
       array array_intersect_key (array  $array1, array  $array2, [array  $...])

DESCRIPTION
       array_intersect_key(3) returns an array containing all the entries of $array1 which have keys that are present in all the arguments.

PARAMETERS
	      o $array1
		- The array with master keys to check.

	      o $array2
		- An array to compare keys against.

	      o $...
		- A variable list of arrays to compare.

RETURN VALUES
	Returns an associative array containing all the entries of $array1 which have keys that are present in all arguments.

EXAMPLES
       Example #1

	      array_intersect_key(3) example

	      <?php
	      $array1 = array('blue'  => 1, 'red'  => 2, 'green'  => 3, 'purple' => 4);
	      $array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan'	 => 8);

	      var_dump(array_intersect_key($array1, $array2));
	      ?>

	      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.

	The  two  keys	from  the key => value pairs are considered equal only if (string) $key1 === (string) $key2 . In other words a strict type
       check is executed so the string representation must be the same.

SEE ALSO
       array_diff(3), array_udiff(3), array_diff_assoc(3), array_diff_uassoc(3), array_udiff_assoc(3),	array_udiff_uassoc(3),	array_diff_key(3),
       array_diff_ukey(3), array_intersect(3), array_intersect_assoc(3), array_intersect_uassoc(3), array_intersect_ukey(3).

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