How to selectmany for enum?

Question

User521171331 posted

Say for example I have this enum

public enum Suit
{
    Diamonds, Clubs, Hearts, Spades
}

How do I use LINQ selectmany to loop my enum four times?

This is version below is not in enum but my version, the Suit is enum

cards = new[] { "Spades", "Hearts", "Clubs", "Diamonds", }
                    .SelectMany(
                        suit => Enumerable.Range(1, 13),
                        (suit, rank) => new Card(rank, suit))
                    .ToArray();

I tried this but it says 'Cannot implicitly convert type 'Card[]' to 'System.Collections.Generic.List<Card>'

var suitAsList = Enum.GetValues(typeof(Suit)).Cast<Suit>().ToList();
        cards =
                suitAsList
                    .SelectMany(
                        suit => Enumerable.Range(1, 13),
                        (suit, rank) => new Card((Suit)suit, (Face)rank))
                    .ToArray();

My working version is below but wish to use LINQ selectmany method

        List<Card> coldDeck = new List<Card>(52);

        for (int j = 0; j < 4; j++)
            for (int i = 0; i < 13; i++)
                coldDeck.Add(new Card((Suit)j, (Face)i));
        cards = coldDeck;

Answer 1

User283571144 posted

Hi ngaisteve1,

According to your codes, I found you ToArray to convert the suitAsList with SelectMany method.  

Since the suitAsList  is a list, it will generate a list after SelectMany method. This is the reason why you get the  'Cannot implicitly convert type 'Card[]' to 'System.Collections.Generic.List<Card>' error.

If you want to get the array result, you could try to use below codes:

            var suitAsList = Enum.GetValues(typeof(Suit)).Cast<Suit>().ToArray();

            var cards =
  suitAsList
            .SelectMany(
                suit => Enumerable.Range(1, 13),
                (suit, rank) => new Card((Suit)suit, rank))
            .ToArray();

Then it will work well.

Best Regards,

Brando

Answer 2

User521171331 posted

thanks. it works.