Question

I am trying to write a frame program that allows you to play Texas Hold’em Poker. And I am having trouble with function hasPair that decides if CurrentPlayer has a Pair:

  public bool hasPair(Player CurrentPlayer)
        {
            bool flag;
            Card[] SevenCards = new Card[7];

            SevenCards[0].Color = CurrentPlayer.Card1.Color;
            SevenCards[0].Number = CurrentPlayer.Card1.Number;
            SevenCards[1].Color = CurrentPlayer.Color2;
            SevenCards[1].Number = CurrentPlayer.Number2;

            SevenCards[2] = Ground.Card1;
            SevenCards[3] = Ground.Card2;
            SevenCards[4] = Ground.Card3;
            SevenCards[5] = Ground.Card4;
            SevenCards[6] = Ground.Card5;

            flag = isThere_Pair(SevenCards); 

            return flag;
        }

And here is how CurrentPlayer receives its cards:

    public void Deal_Cards(Player Player)
    {
        int Color1, No1, Color2, No2;

        while (true)
        {


        dealhelper1:

            Color1 = (RandomColor.Next() % 4);
            No1 = ((RandomNo.Next() % 13));


            if (CardDeck[Color1, No1].isChosen == true)
            {
                goto dealhelper1;
            }

            if (CardDeck[Color1, No1].isChosen == false)
            {
                Player.Card1.Color = Color1;

                Player.Card1.Number = No1+1;
                Player.Card1.imagePath = CardDeck[Color1, No1].imagePath;

                Player.Color1 = CardDeck[Color1, No1].Color;
                Player.Number1 = CardDeck[Color1, No1].Number;                   

                CardDeck[Color1, No1].isChosen = true;
                break;
            }
        }

        while (true)
        {
            dealhelper2:

            Color2 = (RandomColor.Next() % 4);
            No2 = ((RandomNo.Next() % 13));

            if (CardDeck[Color2, No2].isChosen == true)
            {
                goto dealhelper2;
            }

            if (CardDeck[Color2, No2].isChosen == false)
            {
                CardDeck[Color2, No2].isChosen = true;


                Player.Card2.Color = Color2;
                Player.Card2.Number = (No2)+1;

                Player.Color2 = CardDeck[Color2, No2].Color;
                Player.Number2 = CardDeck[Color2, No2].Number;
                break;
            }
        }

        display_Player_Cards(Player);
    }

But in the hasPair function, CurrentPlayer‘s cards’ numbers and colors are 0. I tried it in different ways but when I ask in a query, i cannot get the player cards’ number values, although they have been initialized by the Deal_Cards function. Ground’s cards have no problem, though.

interestingly, display_Player_Cards(Player) function works correctly (so it takes the values successfully and displays the cards) .

I use public variables of type Player (struct) like:

    public Player P1 = new Player();
    public Player AI = new Player();

Why can’t they hold their values? How can I solve this issue?
Thanks for help.

Answer 1

The issue your running into here is that struct’s are passed by value in .Net. Hence the Deal_Cards method receives a copy of the Player instance and assigns cards to that copy. The original value passed to Deal_Cards is unmodified.

To fix this you need to either make Player a class or pass it by reference. I highly recomend making Player a class. Having mutable structs is just a path to pain and hard to track down bugs like this.