cards.c

#include <stdio.h>
#include <stdlib.h>
#include <cs50.h>
#include <time.h>

#define DECK_SIZE 52

// strings for pretty printing values
string ranks[] = {"", "A", "2", "3", "4", "5", "6",
                    "7", "8", "9", "10", "J", "Q", "K"};
string suits[] = {"♥", "♣", "♠", "♦"};

// each card has two properties
typedef struct
{
    int suit;
    int rank;
} card;

// function prototypes
card deal_card();
void shuffle();

card deck[DECK_SIZE];

// keeps track of the next card to deal
// increment this every time you deal a card
// shuffle and reset this to 0 to start a new game
int next_card = 0;


int main(void)
{
    // seed the rng
    srand(time(0));
    // create the deck of unique cards
    int n = 0;
    for (int s = 0; s < 4; s++)
    {
        for (int r = 1; r <= 13; r++)
        {
            deck[n].rank = r;
            deck[n].suit = s;
            n++;
        }
    }

    shuffle();

    // example: deal 5 random cards
    printf("Your hand:\n");
    for (int i = 0; i < 5; i++)
    {
        card c = deal_card();
        printf("%s of %s\n", ranks[c.rank], suits[c.suit]);
    }
}


// performs a Fisher-Yates shuffle on the deck
void shuffle()
{
    next_card = 0;
    for (int i = DECK_SIZE - 1; i > 0; i--)
    {
        int j = rand() % (i + 1);
        card tmp = deck[i];
        deck[i] = deck[j];
        deck[j] = tmp;
    }
}


// returns the next card in the deck
// make sure you've shuffled first!
card deal_card()
{
    card c = deck[next_card];
    next_card++;
    return c;
}