How can I cast int to enum?

Question

How can an int be cast to an enum in C#?

Answer 1

You should build in some type matching relaxation to be more robust.

public static T ToEnum(dynamic value)
{
    if (value == null)
    {
        // default value of an enum is the object that corresponds to
        // the default value of its underlying type
        // https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/default-values-table
        value = Activator.CreateInstance(Enum.GetUnderlyingType(typeof(T)));
    }
    else if (value is string name)
    {
        return (T)Enum.Parse(typeof(T), name);
    }

    return (T)Enum.ToObject(typeof(T),
             Convert.ChangeType(value, Enum.GetUnderlyingType(typeof(T))));
}

Test Case

[Flags]
public enum A : uint
{
    None  = 0, 
    X     = 1 < 0,
    Y     = 1 < 1
}

static void Main(string[] args)
{
    var value = EnumHelper.ToEnum(7m);
    var x = value.HasFlag(A.X); // true
    var y = value.HasFlag(A.Y); // true

    var value2 = EnumHelper.ToEnum("X");

    var value3 = EnumHelper.ToEnum(null);

    Console.ReadKey();
}