什么是用C＃返回两个列表的最佳方式？ [英] What is the best way to return two lists in C#?

问题描述

我几乎不好意思问这个问题，但很长一段时间的C程序员，我觉得，也许我不知道在C＃中做到这一点的最好办法。

I am almost embarrassed to ask this question, but as a long time C programmer I feel that perhaps I am not aware of the best way to do this in C#.

我有我需要返回自定义类型的两个列表的成员函数（列表< MyType的> ），我事先知道我将永远有一个返回值。只有两种这些名单

I have a member function that I need to return two lists of a custom type (List<MyType>) and I know beforehand that I will always have a return value of only two of these lists.

最明显的选项是：

public List<List<MyType>> ReturnTwoLists();

或

public void ReturnTwoLists(ref List<MyType> listOne, ref List<myType> listTwo);

两者似乎非最优

Both seem to be non-optimal.

关于如何提高这个有什么建议？

Any suggestions on how to improve this?

第一种方法并不能使它在正在返回只有2列出的语法清晰，第二个使用引用而不是一个返回值，这似乎让非C＃。

The first way doesn't make it clear in the syntax that only 2 lists are being returned, and the second uses references rather then a return value, which seem so non-c#.

推荐答案

首先，这大概应该是退出，而不是 REF 。

First of all, that should probably be out, not ref.

第二，你可以声明并返回。键入包含两个列表

Second, you can declare and return a type containing the two lists.

第三，你可以声明泛型元组键，返回的是一个实例：

Third, you can declare a generic Tuple and return an instance of that:

class Tuple<T,U> {
   public Tuple(T first, U second) { 
       First = first;
       Second = second;
   }
   public T First { get; private set; }
   public U Second { get; private set; }
}

static class Tuple {
   // The following method is declared to take advantage of
   // compiler type inference features and let us not specify
   // the type parameters manually.
   public static Tuple<T,U> Create<T,U>(T first, U second) {
        return new Tuple<T,U>(first, second);
   }
}

return Tuple.Create(firstList, secondList);

您可以扩展这个想法不同数量的物品。

You can extend this idea for different number of items.

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