C# – How to Cast Int to Enum

c++castingenumsinteger

How do I cast an int to an enum in C#?

Best Answer

From an int:

YourEnum foo = (YourEnum)yourInt;

From a string:

YourEnum foo = (YourEnum) Enum.Parse(typeof(YourEnum), yourString);

// The foo.ToString().Contains(",") check is necessary for 
// enumerations marked with a [Flags] attribute.
if (!Enum.IsDefined(typeof(YourEnum), foo) && !foo.ToString().Contains(","))
{
    throw new InvalidOperationException(
        $"{yourString} is not an underlying value of the YourEnum enumeration."
    );
}

From a number:

YourEnum foo = (YourEnum)Enum.ToObject(typeof(YourEnum), yourInt);

Related Solutions

C# Casting – How to Cast Ints to Enums

Guessing about 'why' is always dangerous, but consider this:

enum Direction { North =1, East = 2, South = 4, West = 8 }
Direction ne = Direction.North | Direction.East;

int value = (int) ne; // value == 3
string text = ne.ToString();  // text == "3"

When the [Flags] attribute is put in front of the enum, that last line changes to

string text = ne.ToString();  // text == "North, East"

C# – How to Cast Generic Enum to Int

You could also cast your value to object first and then to int.

###C# 7.3 and above

With the Enum generic constraint.

public static int EnumToInt<TValue>(this TValue value) where TValue : Enum
    => (int)(object)value;

###Below C# 7.3

Without the Enum generic constraint.

public static int EnumToInt<TValue>(this TValue value)  where TValue : struct, IConvertible
{
    if(!typeof(TValue).IsEnum)
    {
        throw new ArgumentException(nameof(value));
    }

    return (int)(object)value;
}

If your enum inherits from other types for example from byte the cast to int will throw an InvalidCastException.

You could either check if the base type of the enum is an integer.

public static int EnumToInt<TValue>(this TValue value) where TValue : Enum
{
    if (!typeof(int).IsAssignableFrom(Enum.GetUnderlyingType(typeof(TValue))))
        throw new ArgumentException(nameof(TValue));

    return (int)(object)value;
}

Or you if you use Convert.ToInt32 it will use the IConvertible interface of int32 to convert the incompatible types.

public static int EnumToInt<TValue>(this TValue value) where TValue : Enum
    => Convert.ToInt32(value);

Just be aware the converting uint to int and signed/unsigned pairs can cause unintended behavior. (Boxing to IConvertible and the converting is less performant than just unboxing.)

Best Answer

Related Solutions

C# Casting – How to Cast Ints to Enums

C# – How to Cast Generic Enum to Int

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