php计算二维数组中某一项之和的方法

数组示例：

  [0] => array(3) {     ["id"] => string(1 "1"     ["name"] => string(4) "jhon"     ["amount"] => string(3) "850"    }  [1] => array(3) {     ["id"] => string(1) "2"     ["name"] => string(5) "david"     ["amount"] => string(4) "1200"    }  [2] => array(3) {     ["id"] => string(1) "3"     ["name"] => string(4) "lucy"     ["amount"] => string(3) "200"    }

需求说明：计算数组中所有元素的amount项的和。

方法一：

  $total = array_sum(array_map(function($val){return $val['amount'];}, $arr));

方法二：

  $total = 0;  foreach($arr as $item){      $total += (int) $item['amount'];  }