How to get next (or previous) enum value in C#

Question

I have an enum which is defined like this:

public enum eRat { A = 0, B=3, C=5, D=8 };

So given value eRat.B, I want to get the

Answer 1

You can add and remove integers to an enum to obtain the next value. The only problem is that integer operations on the enum will not check the validity of the enum itself, thus could set "invalid" values.

But you can combine the ++enum and the Enum.IsDefined() to obtain a simple way to get next and previous values of your enum. This would be inefficient in your case since the integer values are not continuous, but if you have continuous integers then it works nicely, and one can check when the ++enum is out of range. Check the next example.

 public enum level
    {
        a = 0,
        b = 1,
        c = 2,
        d = 3,
        e = 4
    }

private static void Main(string[] args)
    {
        var levelValue = level.a;
        Console.WriteLine(levelValue);
        ++levelValue;
        Console.WriteLine(levelValue);
        ++levelValue;
        Console.WriteLine(levelValue);
        ++levelValue;
        Console.WriteLine(levelValue);
        ++levelValue;
        Console.WriteLine(levelValue);
        ++levelValue;
        Console.WriteLine(Enum.IsDefined(typeof(Program.level), levelValue));
        Console.WriteLine(levelValue);
        --levelValue;
        Console.WriteLine(levelValue);
        --levelValue;
        Console.WriteLine(levelValue);
        --levelValue;
        Console.WriteLine(levelValue);
        --levelValue;
        Console.WriteLine(levelValue);
        --levelValue;
        Console.WriteLine(Enum.IsDefined(typeof(Program.level), levelValue));
        Console.WriteLine(levelValue);
        --levelValue;
        Console.WriteLine(Enum.IsDefined(typeof(Program.level), levelValue));
        Console.WriteLine(levelValue);
    }

The output for this would be:

a
b
c
d
e
False
5
e
d
c
b
True
a
False
-1