PHP array_diff() 函數的坑

此次在項目中使用 array_diff 函數被坑了. 有以下兩個二維數組:

$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"),
);

求這兩個數組的差集, 用 array_diff() 函數:

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

var_dump($ary3);

輸出結果爲array(0) {}, 哈哈, 是否是很坑啊.

若是用在一維數組上, 也只比較了值, 並無比較鍵, 也就是說只要值是同樣的, 就會被剔除掉, 而無論鍵是否同樣, 例如:

$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);

輸出結果爲:Array ( [b] => green [c] => blue )

若是要鍵也參與比較則須要使用 array_diff_assoc() 函數