最近在寫一個項目 項目中 涉及到數組差集問題 代碼如下 <?php $arr1 = [ [ "cardId" => 1010284722, "beforeAmounts" => 100, "afterAmounts" => 20, "diffAmounts" => -80, "diffStatus" => 1 ], [ "cardId" => 1010284722, "beforeAmounts" => 100, "afterAmounts" => 200, "diffAmounts" => 100, "diffStatus" => 0 ], [ "cardId" => 177561410, "beforeAmounts" => 2000, "afterAmounts" => 1000, "diffAmounts" => -1000, "diffStatus" => 1 ], [ "cardId" => 177561410, "beforeAmounts" => 2000, "afterAmounts" => 1000, "diffAmounts" => -1000, "diffStatus" => 1 ], [ "cardId" => 1077060068, "beforeAmounts" => 789, "afterAmounts" => 100, "diffAmounts" => -689, "diffStatus" => 1 ], [ "cardId" => 1077060068, "beforeAmounts" => 789, "afterAmounts" => 100, "diffAmounts" => -689, "diffStatus" => 1 ] ]; $arr2 = [ [ "cardId" => 177561410, "beforeAmounts" => 2000, "afterAmounts" => 1000, "diffAmounts" => -1000, "diffStatus" => 1 ], [ "cardId" => 1077060068, "beforeAmounts" => 789, "afterAmounts" => 100, "diffAmounts" => -689, "diffStatus" => 1 ] ]; echo 'arr1個數:'.count($arr1).'<br /><br />'; echo 'arr1集合: '; var_dump($arr1); echo '<hr />'; echo 'arr2個數:'.count($arr2).'<br /><br />'; echo 'arr2集合: '; var_dump($arr2); echo '<hr />'; //這是我求差集的方法 foreach($arr1 as $k=>$v) if(in_array($v, $arr2)) unset($arr1[$k]); echo '差集個數:'.count($arr1).'<br /><br />'; echo '差集集合：'; var_dump($arr1); 因為有重復的數據 這樣求出來之后 差集的個數 + $arr2 的個數 不等于 $arr1 的個數 問 ： 怎么樣求差集才能 差集的個數 + $arr2 的個數 = $arr1 的個數 而且最后求出的差集 集合也包含那兩個重復的數組元素 "cardId" => 177561410 和 "cardId" => 1077060068