Replace values in first associative array ($a1) with values in second array ($a2) with extra keys in PHP

Description

The following code shows how to replace values in first associative array ($a1) with values in second array ($a2) with extra keys.

Example

/*w w  w  .j  av a 2 s  . com*/
//If a key exists in array2 and not in array1

<?php
    $a1=array("a"=>"red","green");
    $a2=array("a"=>"orange","b"=>"Basic");
    print_r(array_replace($a1,$a2));
?>

The code above generates the following result.