<?php
date_default_timezone_set('Asia/Shanghai');
$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
)