Playing card data structure?

**crypticgeek** · 12-30-2006

I've decided to write a texas hold'em game that can be played solitare style, just for kicks.

Anyway, I'm hung up on the best way to represent the cards. I have a class Card that contains a pair of ints, one for the suit and the other for rank. Then a deck would just be an array of Cards, etc. Now, I want to spit the value of these cards onto the console. What's the best way to do this? Just using switch statements? Is there some way to have a global hash table that Card can access? Something else?

(sorry if this is better off in the game forum, I couldn't decide where to stick this)

**Dave_Sinkula** · 12-30-2006

How about just use an int for the card? You can get rank and suit easily from this value.

Code:

   int r = value % 13;
   int s = value / 13;

Also, you could even apply this technique to have multiple decks in the shoe.

**Bench82** · 12-30-2006

Personally, I would store the cards in an STL container, such as a vector - this would allow you to easily add/remove cards from the deck. (You may want to transfer them from a container holding the deck, to a container holding the player's current hand, or maybe a discard pile, depending on the card game.)

assuming you've got something like

Code:

struct card_type
{
    int rank;  // number from 0 to 12
    int suit;  // number from 0 to 3
}

you could hold tables of words to output to the screen.. (Again, maybe better to put these into a vector<string> )

Code:

const std::string suits[] = { "Hearts", "Diamonds", "Clubs", "Spades" };
const std::string ranks[] = { "Ace", "Two",  "Three", /* ... */ "Jack", "Queen", "King" };

which may be represented something like this...

Code:

card_type mycard;
mycard.rank = 2;
mycard.suit = 1;   //You'd probably have gotten these values another way

std::cout << "You have the " << ranks[mycard.rank] 
          << " of " << suits[mycard.suit] << std::endl;

This is a minimalist example without error checking, so you'd need to add some data validation before accessing any array elements.

**dwks** · 12-30-2006

You're missing a ".

Code:

const std::string suits[] = { "Hearts", "Diamonds", "Clubs", "Spades" };

Is there some way to have a global hash table that Card can access?

You could have a static array instead of a global variable, for the suits for example.

Code:

class Card {
private:
    int rank, suit;
    static const char *suits[], *ranks[];
public:
    const char *get_suit() { return suits[suit]; }
};

const char *Card::suits[] = {"Hearts", "Diamonds", "Clubs", "Spades"};

Or maybe you could have a class Suit to represent this.

**crypticgeek** · 12-30-2006

Originally Posted by dwks

You could have a static array instead of a global variable, for the suits for example.

Code:

class Card {
private:
    int rank, suit;
    static const char *suits[], *ranks[];
public:
    const char *get_suit() { return suits[suit]; }
};

const char *Card::suits[] = {"Hearts", "Diamonds", "Clubs", "Spades"};

The problem with this is these arrays would be created for every card, right?

**crypticgeek** · 12-30-2006

Originally Posted by Bench82

Personally, I would store the cards in an STL container, such as a vector - this would allow you to easily add/remove cards from the deck.

Actually I already had 'em in a vector. To shuffle, a simple call to random_shuffle is all that's needed.

**crypticgeek** · 12-30-2006

Originally Posted by Dave_Sinkula

How about just use an int for the card? You can get rank and suit easily from this value.

Code:

   int r = value % 13;
   int s = value / 13;

Also, you could even apply this technique to have multiple decks in the shoe.

Certainly another way to do it. For convenience sake I was going to store them in a pair<int, int> for passing around and such.

It's a toss up really. Do you use one int (really could be a char if we were concerned that much about memory use) and take the processing time to do the mods and divides every time you need to evaluate the card? Or do you use twice as much memory but avoid the computations? If we were talking about anything larger it might be a genuine debate, but really who cares if you use 52 bytes of memory vs 104 bytes of memory...or if you do a couple of mods and divides or not?

Just because I'm lazy, I think I'll store them seperately. Seems like kind of a pain to have to calculate out the values everytime you want to use them.

**robatino** · 12-30-2006

How about

Code:

class Card {
  int value;
public:
  void set_card(int rank, int suit) {value = rank+13*suit;}
  int get_rank() {return value%13;}
  int get_suit() {return value/13;}
};

That minimizes memory use but makes it reasonably easy to use (you can replace int with unsigned char, and modify suitably if you want the rank to go from 1 to 13 instead of from 0 to 12 as it does now).

Edit: Same for suit which presently goes from 0 to 3.

**crypticgeek** · 12-30-2006

Good idea, and I can return them back in a pair for convenience sake. Thanks.

**Bench82** · 12-30-2006