Convert Enum into another Enum

Question

I have two enums:

public enum Fruits
{
    Apple = 1,
    Banana = 2,
    Strawberry = 3,
    Blueberry = 4
}

public enum FruitsCombined
{
    Apple = 1,
    Banana = 2,
    Berries = 0  //Strawberry and Blueberry combined
}

I have a Combobox, which is bound to the FruitsCombined enum, but in the background, when I select Berries, I want to say it's 3 and 4 from the Fruits enum.

How can I do this?

For example, I want to replace this for a better way, with the two enums:

if ((int)cboFilterFruitType.SelectedValue == 0)
{
    order = order.FindAll(o => o.FruitID == 3 || o.FruitID == 4);
}
else
{
    order = order.FindAll(o => o.FruitID == (int) cboFilterFruitType.SelectedValue);
}

You should not use `0` as a value for any meaningful enum value because that's the value of `default(TEnum)`. So you should change `Berries = 0` to `Berries = 3` - or better-yet: `Berries = 7` (because `7 == 3 | 4`). — Dai, Oct 10 '22 at 13:24
Best way is make enum values a power of 2 : Apple = 1, Banana = 2, Strawberry = 4, Blueberry = 8. Then berries will be 12 (8 + 4). — jdweng, Oct 10 '22 at 13:38

score 2 · Accepted Answer · answered Oct 10 '22 at 13:40

You can use flags enums:

[Flags]
public enum Fruits
{
    Apple = 1,
    Banana = 2,
    Strawberry = 4,
    Blueberry = 8
}

public enum FruitsCombined
{
    Apple = 1,
    Banana = 2,
    Berries = Fruits.Strawberry | Fruits.Blueberry //Strawberry and Blueberry combined
}

Now you can cast one to the other:

FruitsCombined fruitCombined = FruitsCombined.Berries;
Fruits fruit = (Fruits)fruitCombined; // Fruits.Strawberry | Fruits.Blueberry

If you want to check if it's a berry you can use Enum.HasFlag:

bool isBerry = fruit.HasFlag(Fruits.Strawberry | Fruits.Blueberry);

score 0 · Answer 2 · answered Oct 10 '22 at 13:36

If you have control over both enums you could combine the enums together using flags like suggested in the comments.

[Flags]
public enum Fruits
{
    None = 0,
    Apple = 1,
    Banana = 2,
    Strawberry = 4,
    Blueberry = 8,
    Berries = Strawberry | Blueberry
}

Then if you had code like this

var fruit = Fruits.Berries;
Console.WriteLine(fruit.HasFlag(Strawberry));
Console.WriteLine(fruit.HasFlag(Blueberry));

Both write lines would print true.

score 0 · Answer 3 · answered Oct 10 '22 at 13:37

as stuartd link says do something more like

change to powers of two

public enum Fruits
{
    Apple = 1,
    Banana = 2,
    Strawberry = 4,
    Blueberry = 8
}

Then you can use bitwise to represent any combo

var appBann = Fruits.Apple | Suits.Banana ;

or Berries = Fruits.Strawberry | Suits.Blueberry

you can even have it as a enum

  public enum Fruits
    {
        Apple = 1,
        Banana = 2,
        Strawberry = 4,
        Blueberry = 8,
        Berries = Strawberry | Blueberry
    }

 order = order.FindAll(o => o.FruitID == (int)Fruits.Berries);

Convert Enum into another Enum

3 Answers3