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

I tried the first solution but it did not work for me. Below is my solution:

    public  object NextEnumItem(object currentEnumItem) 
    {
        if (!currentEnumItem.GetType().IsEnum) throw new 
                ArgumentException(String.Format("Argument is not an Enum"));
        Array Arr = Enum.GetValues(currentEnumItem.GetType());
        int j = Array.IndexOf(Arr,currentEnumItem) + 1;
        return (Arr.Length == j) ? currentEnumItem : Arr.GetValue(j);
    }

    public object PreviousEnumItem(object currentEnumItem)
    {
        if (!currentEnumItem.GetType().IsEnum)
            throw new ArgumentException(String.Format("Argument is not an Enum"));
        Array Arr = Enum.GetValues(currentEnumItem.GetType());
        int j = Array.IndexOf(Arr, currentEnumItem) - 1;
        return (j==-1) ? currentEnumItem : Arr.GetValue(j);
    }