聚集（）中的C＃-终止

Question

根据以下模拟

int[] amountWithdrawal = { 10, 20, 30, 140, 50, 70 };

amountWithdrawal.Aggregate(100, (balance, withdrawal) => 
{
  Console.WriteLine("balance :{0},Withdrawal:{1}", balance, withdrawal);
 if (balance >= withdrawal)
 {
   return balance - withdrawal;
 }
 else return balance;
 }
);

我想when the balance is less than the withdrawal提款额when the balance is less than the withdrawal终止聚合when the balance is less than the withdrawal但是我的代码遍历了整个数组，如何终止它？

Answer 1

在我看来，您想要一种Accumulate方法，该方法可以产生新的累积值序列，而不是标量。 像这样：

public static IEnumerable<TAccumulate> SequenceAggregate<TSource, TAccumulate>(
    this IEnumerable<TSource> source,
    TAccumulate seed,
    Func<TAccumulate, TSource, TAccumulate> func)
{
    TAccumulate current = seed;
    foreach (TSource item in source)
    {
        current = func(current, item);
        yield return current;
    }
}

然后，您可以应用TakeWhile ：

int[] amountWithdrawal = { 10, 20, 30, 140, 50, 70 };

var query = amountWithdrawal.SequenceAggregate(100, (balance, withdrawal) => 
{
  Console.WriteLine("balance :{0},Withdrawal:{1}", balance, withdrawal);
  return balance - withdrawal;
}).TakeWhile (balance => balance >= 0);

我本可以宣誓在普通的LINQ to Objects中有这样的东西，但目前无法找到...

Answer 2

您应该照常使用“ Aggregate ”，然后使用“ Where忽略负余额。

顺便说一句，在LINQ方法内部使用具有副作用的函数（例如Console.WriteLine ）是不好的做法。 您最好先进行所有LINQ聚合和过滤，然后编写一个foreach循环以打印到控制台。

Answer 3

将聚合替换为for循环。

Answer 4

您可能要使用TakeWhile().Aggregate()并检查谓词中take的余额。