Description
array 
array_intersect_key ( array array1, array array2 [, array ...] )
     array_intersect_key() returns an array
     containing all the values of array1
     which have matching keys that are present in all the arguments.
    
     
Example 1. array_intersect_key() 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(),
     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_ukey().