根据索引检索Enum的值 - c#

Question

这是我的枚举:

public enum DocumentTypes
    {
        [EnumMember]
        TYPE_1 = 1,
        [EnumMember]
        TYPE_2 = 2,
        [EnumMember]
        TYPE_3 = 3,
        [EnumMember]
        TYPE_4 = 4,
        [EnumMember]
        TYPE_5 = 5,
        [EnumMember]
        TYPE_6 = 6,
        [EnumMember]
        TYPE_7 = 7,
        [EnumMember]
        TYPE_8 = 12

    }

如果我想获得'TYPE_8',如果我只有12,有没有办法获得枚举值？

我试过这个:

((DocumentTypes[])(Enum.GetValues(typeof(DocumentTypes))))[Convert.ToInt32("3")].ToString()

返回'TYPE_4'的值

Answer 1

你可以直接施放它:

int value = 12;
DocumentTypes dt = (DocumentTypes)value;

Answer 2

string str = "";
int value = 12;
if (Enum.IsDefined(typeof (DocumentTypes),value))
     str =  ((DocumentTypes) value).ToString();
else
     str = "Invalid Value";

这也将处理尝试使用的无效值,而不会抛出内部异常

您还可以使用DocumentTypes替换字符串,即

DocumentTypes dt = DocumentTypes.Invalid; // Create an invalid enum
if (Enum.IsDefined(typeof (DocumentTypes),value))
   dt = (DocumentTypes) value;

对于奖励点,这里是如何将自定义字符串添加到枚举(从此SO答案复制)

Enum DocumentType
{ 
    [Description("My Document Type 1")]
    Type1 = 1,
    etc...
}

然后在某处添加扩展方法

public static string GetDescription<T>(this object enumerationValue) where T : struct
{
    Type type = enumerationValue.GetType();
    if (!type.IsEnum)
        throw new ArgumentException("EnumerationValue must be of Enum type", "enumerationValue");

    //Tries to find a DescriptionAttribute for a potential friendly name
    //for the enum
    MemberInfo[] memberInfo = type.GetMember(enumerationValue.ToString());
    if (memberInfo != null && memberInfo.Length > 0)
    {
        object[] attrs = memberInfo[0].GetCustomAttributes(typeof (DescriptionAttribute), false);

        if (attrs != null && attrs.Length > 0)
        {
            //Pull out the description value
            return ( (DescriptionAttribute) attrs[0] ).Description;
        }
    }
    //If we have no description attribute, just return the ToString of the enum
    return enumerationValue.ToString();
}

然后你可以使用:

DocumentType dt = DocumentType.Type1;
string str = dt.GetDescription<DocumentType>();

这将检索Description属性值.

编辑 - 更新的代码

这是一个新版本的扩展方法,不需要事先知道Enum的类型.

public static string GetDescription(this Enum value)
{
    var type = value.GetType();

    var memInfo = type.GetMember(value.ToString());

    if (memInfo.Length > 0)
    {
        var attrs = memInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), false);
        if (attrs.Length > 0)
            return ((DescriptionAttribute)attrs[0]).Description;
    }

    return value.ToString();
}

Answer 3

首先转换为你的枚举类型并调用ToString():

string str = ((DocumentTypes)12).ToString();