Question

如果我有枚举字符串或枚举int值，如何获取枚举值。例如：如果我有一个枚举如下：

public enum TestEnum
{
    Value1 = 1,
    Value2 = 2,
    Value3 = 3
}

在某些字符串变量中，我的值为“value1”，如下所示：

string str = "Value1"

或在某个int变量中，我的值为2，如

int a = 2;

如何获取枚举实例？我想要一个泛型方法，我可以提供枚举和我的输入字符串或int值来获取枚举实例。

Answer 1

不，您不需要通用方法。这更容易：

MyEnum enum = (MyEnum)myInt;

MyEnum enum = (MyEnum)Enum.Parse(typeof(TestEnum), myString);

我认为它也会更快。

Answer 2

有很多方法可以做到这一点，但如果你想要一个简单的例子，那就可以了。它只需要通过必要的防御性编码来增强，以检查类型安全性和无效解析等。

    /// <summary>
    /// Extension method to return an enum value of type T for the given string.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value"></param>
    /// <returns></returns>
    public static T ToEnum<T>(this string value)
    {
        return (T) Enum.Parse(typeof(T), value, true);
    }

    /// <summary>
    /// Extension method to return an enum value of type T for the given int.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value"></param>
    /// <returns></returns>
    public static T ToEnum<T>(this int value)
    {
        var name = Enum.GetName(typeof(T), value);
        return name.ToEnum<T>();
    }

Answer 3

如果您使用TryParse或Parse和ToObject方法，可能会更简单。

public static class EnumHelper
{
    public static  T GetEnumValue<T>(string str) where T : struct, IConvertible
    {
        Type enumType = typeof(T);
        if (!enumType.IsEnum)
        {
            throw new Exception("T must be an Enumeration type.");
        }
        T val;
        return Enum.TryParse<T>(str, true, out val) ? val : default(T);
    }

    public static T GetEnumValue<T>(int intValue) where T : struct, IConvertible
    {
        Type enumType = typeof(T);
        if (!enumType.IsEnum)
        {
            throw new Exception("T must be an Enumeration type.");
        }

        return (T)Enum.ToObject(enumType, intValue);
    }
}

正如@chrfin在评论中所指出的那样，只需在参数类型之前添加this就可以非常方便地使其成为一种扩展方法。

Answer 4

以下是C＃中按字符串

获取枚举值的方法

    ///
    /// Method to get enumeration value from string value.
    ///
    ///
    ///

    public T GetEnumValue<T>(string str) where T : struct, IConvertible
    {
        if (!typeof(T).IsEnum)
        {
            throw new Exception("T must be an Enumeration type.");
        }
        T val = ((T[])Enum.GetValues(typeof(T)))[0];
        if (!string.IsNullOrEmpty(str))
        {
            foreach (T enumValue in (T[])Enum.GetValues(typeof(T)))
            {
                if (enumValue.ToString().ToUpper().Equals(str.ToUpper()))
                {
                    val = enumValue;
                    break;
                }
            }
        }

        return val;
    }

以下是C＃中通过int获取枚举值的方法。

    ///
    /// Method to get enumeration value from int value.
    ///
    ///
    ///

    public T GetEnumValue<T>(int intValue) where T : struct, IConvertible
    {
        if (!typeof(T).IsEnum)
        {
            throw new Exception("T must be an Enumeration type.");
        }
        T val = ((T[])Enum.GetValues(typeof(T)))[0];

        foreach (T enumValue in (T[])Enum.GetValues(typeof(T)))
        {
            if (Convert.ToInt32(enumValue).Equals(intValue))
            {
                val = enumValue;
                break;
            }             
        }
        return val;
    }

如果我有一个枚举如下：

public enum TestEnum
    {
        Value1 = 1,
        Value2 = 2,
        Value3 = 3
    }

然后我可以使用上述方法

TestEnum reqValue = GetEnumValue<TestEnum>("Value1");  // Output: Value1
TestEnum reqValue2 = GetEnumValue<TestEnum>(2);       // OutPut: Value2

希望这会有所帮助。

Answer 5

我认为您忘记了泛型类型定义：

public T GetEnumValue<T>(int intValue) where T : struct, IConvertible // <T> added

你可以将它改进为最方便，例如：

public static T ToEnum<T>(this string enumValue) : where T : struct, IConvertible
{
    return (T)Enum.Parse(typeof(T), enumValue);
}

然后你可以这样做：

TestEnum reqValue = "Value1".ToEnum<TestEnum>();

Answer 6

从SQL数据库获取枚举，如：

SqlDataReader dr = selectCmd.ExecuteReader();
while (dr.Read()) {
   EnumType et = (EnumType)Enum.Parse(typeof(EnumType), dr.GetString(0));
   ....         
}

Answer 7

只需尝试这个

这是另一种方式

public enum CaseOriginCode
    {
        Web = 0,
        Email = 1,
        Telefoon = 2
    }

public void setCaseOriginCode(string CaseOriginCode)
{
    int caseOriginCode = (int)(CaseOriginCode)Enum.Parse(typeof(CaseOriginCode), CaseOriginCode);
}

这是对您的文章的评论

Answer 8

尝试这样的事情

  public static TestEnum GetMyEnum(this string title)
        {    
            EnumBookType st;
            Enum.TryParse(title, out st);
            return st;          
         }

所以你可以做到

TestEnum en = "Value1".GetMyEnum();

Answer 9

这里是获取字符串/值的示例

    public enum Suit
    {
        Spades = 0x10,
        Hearts = 0x11,
        Clubs = 0x12,
        Diamonds = 0x13
    }

    private void print_suit()
    {
        foreach (var _suit in Enum.GetValues(typeof(Suit)))
        {
            int suitValue = (byte)(Suit)Enum.Parse(typeof(Suit), _suit.ToString());
            MessageBox.Show(_suit.ToString() + " value is 0x" + suitValue.ToString("X2"));
        }
    }

    Result of Message Boxes
    Spade value is 0x10
    Hearts value is 0x11
    Clubs value is 0x12
    Diamonds value is 0x13

Answer 10

您可以使用以下方法进行操作：

combi_sum <- dcast(merge(mtcarsTOTAL[,.(cost, gear)], iris[, .N, .(carb, gear, gender, age)], by = "gear"), 
                gender + age ~ carb, value.var = "cost", fun.aggregate = sum, fill = 0)

structure(list(gender = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), age = c(1L, 2L, 
3L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 13L, 14L, 2L, 3L, 4L, 
5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 1L, 3L, 4L, 5L, 6L, 7L, 8L, 
9L, 11L, 12L, 13L, 14L), `1` = c(978, 978, 0, 0, 1074, 0, 0, 
0, 2642, 2642, 0, 0, 0, 0, 3620, 0, 978, 2642, 0, 0, 978, 0, 
0, 978, 2052, 0, 0, 0, 0, 1074, 978, 0, 0, 0, 3620, 0), `2` = c(0, 
0, 0, 978, 0, 0, 0, 2052, 0, 2642, 978, 0, 0, 0, 0, 0, 0, 0, 
1074, 2642, 0, 0, 0, 0, 0, 0, 0, 1074, 0, 978, 0, 2642, 0, 0, 
978, 2642), `3` = c(0, 0, 0, 0, 0, 978, 2642, 0, 2642, 0, 0, 
2642, 978, 0, 978, 2642, 0, 0, 0, 0, 1074, 3620, 2642, 0, 0, 
0, 978, 0, 2642, 0, 0, 2642, 0, 2642, 0, 0), `4` = c(0, 0, 1074, 
0, 0, 0, 978, 0, 0, 0, 1074, 1074, 0, 2052, 0, 0, 0, 0, 0, 1074, 
0, 2642, 1074, 978, 978, 2642, 0, 0, 2642, 0, 2052, 0, 2642, 
1074, 0, 0)), row.names = c(NA, -36L), class = c("data.table", 
"data.frame"), .internal.selfref = <pointer: 0x7fb24d802ee0>, sorted = c("gender", 
"age"))

combi_length <- dcast(merge(mtcarsTOTAL[,.(cost, gear)], iris[, .N, .(carb, gear, gender, age)], by = "gear"), 
                   gender + age ~ carb, value.var = "cost", fun.aggregate = length, fill = 0)

structure(list(gender = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), age = c(1L, 2L, 
3L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 13L, 14L, 2L, 3L, 4L, 
5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 1L, 3L, 4L, 5L, 6L, 7L, 8L, 
9L, 11L, 12L, 13L, 14L), `1` = c(1L, 1L, 0L, 0L, 1L, 0L, 0L, 
0L, 1L, 1L, 0L, 0L, 0L, 0L, 2L, 0L, 1L, 1L, 0L, 0L, 1L, 0L, 0L, 
1L, 2L, 0L, 0L, 0L, 0L, 1L, 1L, 0L, 0L, 0L, 2L, 0L), `2` = c(0L, 
0L, 0L, 1L, 0L, 0L, 0L, 2L, 0L, 1L, 1L, 0L, 0L, 0L, 0L, 0L, 0L, 
0L, 1L, 1L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 1L, 0L, 1L, 0L, 1L, 0L, 
0L, 1L, 1L), `3` = c(0L, 0L, 0L, 0L, 0L, 1L, 1L, 0L, 1L, 0L, 
0L, 1L, 1L, 0L, 1L, 1L, 0L, 0L, 0L, 0L, 1L, 2L, 1L, 0L, 0L, 0L, 
1L, 0L, 1L, 0L, 0L, 1L, 0L, 1L, 0L, 0L), `4` = c(0L, 0L, 1L, 
0L, 0L, 0L, 1L, 0L, 0L, 0L, 1L, 1L, 0L, 2L, 0L, 0L, 0L, 0L, 0L, 
1L, 0L, 1L, 1L, 1L, 1L, 1L, 0L, 0L, 1L, 0L, 2L, 0L, 1L, 1L, 0L, 
0L)), row.names = c(NA, -36L), class = c("data.table", "data.frame"
), .internal.selfref = <pointer: 0x7fb24d802ee0>, sorted = c("gender", 
"age"))

注意：此方法仅是示例，您可以对其进行改进。

如何通过string或int获取枚举值

10 个答案: