php compare two arrays for matches code example

Example: array_intersect php

<?php
$a1 = array("a"=>"red", "b"=>"green", "c"=>"blue", "d"=>"yellow");
$a2 = array("e"=>"red", "f"=>"green", "g"=>"blue");

$result = array_intersect($a1, $a2);
print_r($result); //Array ( [a] => red [b] => green [c] => blue )