使用Linq C＃进行求和和减法

Question

我只需要返回一个结果，我需要将所有状态500.html和(1, 3)相加，然后减去每个结果：

(2, 4, 5)

我试过：

cashtransaction_amount, cashtransactionstatus_id
50.00                   1 (+)
39.99                   2 (-)
330.70                  3 (+)
10.00                   5 (-)
50.50                   4 (-)
30.00                   2 (-)

Sum(1,3): 50.00 + 330.70 = 380.70
Sum(2, 5, 4): 39.99 + 10.00 + 50.50 + 30.00 = 130.49
Final Result Sum(1,3) - Sum(2, 5, 4): 380.70 - 130.49 = 250.21

Answer 1

你试过吗

cashtransaction_amount = tmp.Aggregate((a,b) =>
    {
        var id = b.Field<Int32>("cashtransactionstatus_id");
        var amt = b.Field<Double>("cashtransaction_amount");
        return id == 1 || id == 3 ? a + amt : a - amt;
    });

Answer 2

另一种方式是：

total = tmp.Select(b =>
           {
               var id = b.Field<Int32>("cashtransactionstatus_id");
               return (id == 1 || id == 3 ? 1 : -1) *
                      b.Field<Double>("cashtransaction_amount");
           }).Sum();

或者：

total = tmp.Sum(b => (new[]{1,3}.Contains(b.Field<Int32>("cashtransactionstatus_id"))
                          ? 1 : -1) * b.Field<Double>("cashtransaction_amount"));