Similar to array_merge(), this function combines two or more arrays into one.

The main differences with this function are:

  1. Any duplicate key will be overwritten (not just string keys)
  2. Nothing is re-indexed

It goes through the arrays listed - in order - and any existing keys have their values overwritten. Any new keys are appended to the end of your new array.

$arr1 = array( 'a' => 'apple',
               'b' => 'banana',
               'c' => 'carrot' );
$arr2 = array( 'b' => 'ball',
               2   => 'stick',
               17  => 'monkey' );
$arr3 = array( 'a' => 'zebra',
               'b' => 'yak' );
 
$new_a = array_replace( $arr1, $arr2, $arr3 );
/*
array (
  'a' => 'zebra',
  'b' => 'yak',
  'c' => 'carrot',
  2 => 'stick',
  17 => 'monkey'
)
*/
 
// order is important
$new_b = array_replace( $arr1, $arr3, $arr2 );
/*
array (
  'a' => 'zebra',
  'b' => 'ball',
  'c' => 'carrot',
  2 => 'stick',
  17 => 'monkey'
)
*/
See the manual entry for array_replace()