C#enum添加

Question

问候,我有以下枚举:

    public enum LegalShipTypes : byte
    {
        Frigate = 1,
        Cruiser = 2,
        Destroyer = 3,
        Submarine = 4,
        AircraftCarrier = 5
    }

我想知道是否有办法以任何方式获得枚举的总价值.例如,这将导致(1 + 2 + 3 + 4 + 5)= 15.

谢谢.

Answer 1

如果你可以编辑枚举,并且你需要在许多地方使用它们的总和,你可以把它放在枚举本身:

public enum LegalShipTypes : byte {
  Frigate = 1,
  Cruiser = 2,
  Destroyer = 3,
  Submarine = 4,
  AircraftCarrier = 5,
  All = Frigate + Cruiser + Destroyer + Submarine + AircraftCarrier
} 

这在标志枚举中更有意义:

[Flags]
public enum LegalShipTypes : byte {
  Frigate = 1,
  Cruiser = 2,
  Destroyer = 4,
  Submarine = 8,
  AircraftCarrier = 16,
  All = Frigate | Cruiser | Destroyer | Submarine | AircraftCarrier
} 

或者你可以使用这个:

Enum.GetValues(typeof(LegalShipTypes)).Cast<byte>().Sum(x=>x)

哪个返回一个decimal.

但这是一种更通用的方法(无论枚举的基础类型如何都有效):

public decimal Sum(Type enumType) {
  return Enum
    .GetValues(enumType)
    .Cast<object>()
    .Sum(x => (decimal)Convert.ChangeType(x, typeof(decimal)));
}

Answer 2

我不想输入这个作为答案,因为它没有直接回答你的问题,而是根据你对我的问题评论的评论,这值得一些解释.

枚举意味着非常简单的类型安全的状态表示.如果只使用常量,则可以将错误的常量分配给值.这可以防止您为字段分配错误类型的常量.例如,如果您有一些需要DayOfWeek的东西,则无法分配FileAccess值,即使它们都是相同底层类型的常量.

DayOfWeek day = FileAccess.Write; // doesn't work

如果你需要这种类型的安全性,并且你不需要你的枚举表现出任何其他类型的行为,那么使用枚举.如果你关心你的枚举也做其他事情(比如枚举,数学运算等),那么你应该考虑使用类.请参阅下面的示例.

public class LegalShipTypes
{
    private readonly byte _numericValue;
    private readonly string _text;

    private LegalShipTypes(byte numericValue, string text)
    {
        _numericValue = numericValue;
        _text = text;
    }

    public byte Value { get { return _numericValue; } }
    public string Text { get { return _text; } }

    public static IEnumerable<LegalShipTypes> All
    {
        get
        {
            return new[] { Frigate, Cruiser, Destroyer, Submarine, AircraftCarrier };
        }
    }

    public static readonly LegalShipTypes Frigate = new LegalShipTypes(1, "Frigate");
    public static readonly LegalShipTypes Cruiser = new LegalShipTypes(2, "Cruiser");
    public static readonly LegalShipTypes Destroyer = new LegalShipTypes(3, "Destroyer");
    public static readonly LegalShipTypes Submarine = new LegalShipTypes(4, "Submarine");
    public static readonly LegalShipTypes AircraftCarrier = new LegalShipTypes(5, "Aircraft Carrier");
}

现在你可以像这样以类型安全的方式使用它:

public class Fleet
{
    private readonly List<LegalShipTypes> _ships;

    public Fleet()
    {
        _ships = new List<LegalShipTypes>();
    }

    public LegalShipTypes Flagship { get; set; }
    public ICollection<LegalShipTypes> Ships { get { return _ships; } }
}

....

var fleet = new Fleet();
fleet.FlagShip = LegalShipTypes.AircraftCarrier;
var iDoNotKnowWhyYouWouldNeedThisBut = LegalShipTypes.All.Sum(ship => ship.Value);
Console.WriteLine("The flagship is a(n) \"{0}\".", fleet.FlagShip.Text);
if (fleet.FlagShip == LegalShipTypes.AircraftCarrier) // this will work because it's a reference comparison
    Console.WriteLine("This should be true");

如您所见,您仍然具有类型安全性,但更具灵活性.这是更多的代码,但你不会发现自己正在努力克服枚举的局限性.重申一下,枚举意味着简单.它应该很简单.如果您的需求很简单,请不要犹豫,使用它.如果您的需求更加复杂,那么使用优秀的老式面向对象编程来解决您的问题并不是一件好事.

编辑

根据您的上一个评论响应,字节值表示挂钩的数量,我强烈建议您不要使用枚举来解决您的问题.(具有讽刺意味的是)你试图在方孔中放一个圆钉.

Answer 3

尝试以下假设它是一个继承自System.Int32的枚举(这是默认值).

public int Sum(Type enumType) {
  return Enum.GetValues(enumType).Cast<int>().Sum();
}

编辑没有注意到OP的问题继承自byte.这是一个适用的版本byte

public int Sum(Type enumType) {
  return Enum.GetValues(enumType).Cast<byte>().Select(x => (int)x).Sum();
}