枚举的初始值 [英] Initial Value of an Enum

问题描述

我有这是一个枚举属性类

I have a class with a property which is an enum

枚举是

/// <summary>
/// All available delivery actions
/// </summary>
public enum EnumDeliveryAction
  {
    /// <summary>
    /// Tasks with email delivery action will be emailed
    /// </summary>
    Email,

    /// <summary>
    /// Tasks with SharePoint delivery action 
   /// </summary>
   SharePoint
  }

当我创建这个类的一个实例，芳踪代码中，我指定的枚举字段的值，但它似乎默认为第一个项目在enumlist，而不是一个空值，这是枚举是如何工作的？这怎么可能，以确保枚举得到某种如果没有设置null值的，我不希望它默认为在枚举的第一个值。

When I create an instance of this class, NOWHERE in the code, do I specify the value of the enum field, but it seems to default to the first item in the enumlist, and not a null value, is this how enums work? How is it possible to ensure that the enum gets some kind of null value if it is not set, I don't want it defaulting to the first value in the enum.

推荐答案

的枚举类型的默认值是 0 （这是在默认情况下，枚举中的第一个元素）。一类的字段将被初始化为默认值。

Default value for enum types is 0 (which is by default, the first element in the enumeration). Fields of a class will be initialized to the default value.

如果您需要代表的未知的在枚举值，您可以添加元素未知值为0。或者，你可以声明字段为可空< MyEnum> （ MyEnum？）。

If you need to represent an unknown value in the enum, you can add an element Unknown with value 0. Alternatively, you could declare the field as Nullable<MyEnum> (MyEnum?).

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