How to get enum value by string or int

How can I get the enum value if I have the enum string or enum int value. eg: If i have an enum as follows:

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

and in some string variable I have the value "value1" as follows:

string str = "Value1" 

or in some int variable I have the value 2 like

int a = 2;

how can I get the instance of enum ? I want a generic method where I can provide the enum and my input string or int value to get the enum instance.

No, you don't want a generic method. This is much easier:

MyEnum myEnum = (MyEnum)myInt;

MyEnum myEnum = (MyEnum)Enum.Parse(typeof(MyEnum), myString);

I think it will also be faster.

There are numerous ways to do this, but if you want a simple example, this will do. It just needs to be enhanced with necessary defensive coding to check for type safety and invalid parsing, etc.

    /// <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>();
    }

Could be much simpler if you use TryParse or Parse and ToObject methods.

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.");
        }
        return Enum.TryParse(str, true, out T val) ? val : default;
    }

    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);
    }
}

As noted by @chrfin in comments, you can make it an extension method very easily just by adding this before the parameter type which can be handy.

Following is the method in C# to get the enum value by string

///
/// 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;
}

Following is the method in C# to get the enum value by int.

///
/// 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;
}

If I have an enum as follows:

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

then I can make use of above methods as

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

Hope this will help.

As suggested by @Phil B in the comments of @Kendall Frey's answer, this can be done quite concisely for strings.

Enum.Parse<MyEnum>(myString);

Adding this since @Kendall Frey's answer gave me a runtime error while @Phil B's revision did not.

I think you forgot the generic type definition:

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

and you can improve it to be most convinient like e.g.:

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

then you can do:

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

Try something like this

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

So you can do

TestEnum en = "Value1".GetMyEnum();

Simply try this

It's another way

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

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

From SQL database get enum like:

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

Here is an example to get string/value

    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

You could use following method to do that:

public static Output GetEnumItem<Output, Input>(Input input)
    {
        //Output type checking...
        if (typeof(Output).BaseType != typeof(Enum))
            throw new Exception("Exception message...");

        //Input type checking: string type
        if (typeof(Input) == typeof(string))
            return (Output)Enum.Parse(typeof(Output), (dynamic)input);

        //Input type checking: Integer type
        if (typeof(Input) == typeof(Int16) ||
            typeof(Input) == typeof(Int32) ||
            typeof(Input) == typeof(Int64))

            return (Output)(dynamic)input;

        throw new Exception("Exception message...");
    }

Note:this method only is a sample and you can improve it.

In this moment its possible to use the Enum.TryParse method:

MyType myType;
bool isValidEnum = Enum.TryParse(yourStringValue, out myType);

If "yourStringValue" is not of MyType enum type then isValidEnum is false.

Regards.