PHP array_diff() 函数的坑

$ary1 = array(
        array('uid'=>1,'name' => "zhangsan1"),
        array('uid'=>2,'name' => "zhangsan2"),
        array('uid'=>3,'name' => "zhangsan3"),
        array('uid'=>4,'name' => "zhangsan4"),
);

$ary2 = array(
        array('uid'=>3,'name' => "zhangsan2"),
        array('uid'=>4,'name' => "zhangsan3"),
);

$ary3 = array_diff($ary1, $ary2);

var_dump($ary3);

$a1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$a2=array("e"=>"red","f"=>"black","g"=>"purple");
$a3=array("a"=>"red","b"=>"black","j"=>"yellow");

$result=array_diff($a1,$a2,$a3);
print_r($result);