EDIT: Literally 1 second after I pressed the post button I got an idea and thats what it was. Why does that always happen? xD

The solution was that my player_hand[] and dealer_hand[] arrays had a size of DECK_SIZE / 2, but I was initialising them to 0 from within the for loop where I was initialising the deck[] array (which has a size of DECK_SIZE), so the last 24 0s of one of those where overflowing into deck[]…

Hello everyone!

I am trying to make a simple blackjack (21) game in C, to practice some pointer stuff, and I am running into an issue with the function that initialises all my arrays. The way I am going about setting everything up, I have an integer array for a standard deck of 52 cards (values from 1 to 13, each 4 times), an integer array for the shuffled deck, and 2 more arrays for the player and dealer hands (irrelevant at this point as they are not used yet).

My issue is that after successfully initialising the deck array (the non-shuffled one) and outputting the values from within the for loop that sets them, I get what I expect to see which is:

1, 2, 3, …, 13, 1, 2, 3, …, 13, … (so on for 52 cards).

But when I output each value from a different for loop in the same function, the first 24 elements (0-23) are 0s each time I run it. I can not figure out why that would be. I ran my program through valgrind which reported that there were no memory leaks.

Here is the relevant code:

#define DECK_SIZE 52

int initialise_decks(int* deck, int* shuffled_deck, int* player_hand, int* dealer_hand, int size)
{
	printf("=================INITIALISING==================\n");
	for (int i = 0; i < size; i++)
	{
		deck[i] = (i % 13) + 1;
		player_hand[i] = 0;
		dealer_hand[i] = 0;

		printf("deck[%d]: %d\n", i, deck[i]);
	}

	printf("+++++++++++++++++++++++++++++++++++++++\n");
	for (int i = 0; i < size; i++)
	{
		printf("deck[%d]: %d\n", i, deck[i]);
	}
	printf("+++++++++++++++++++++++++++++++++++++++\n");


	return INITIALISE_DECKS_SUCCESS;
}

int main() {
	srand(time(0));

	int deck[DECK_SIZE];
	int shuffled_deck[DECK_SIZE];
	int player_hand[DECK_SIZE / 2];
	int dealer_hand[DECK_SIZE / 2];

	int initialise_status = initialise_decks(deck, shuffled_deck, player_hand, dealer_hand, DECK_SIZE);
	if (initialise_status != INITIALISE_DECKS_SUCCESS)
	{
		return INITILIASE_DECKS_FAIL;
	}

	return PROCESS_EXIT_NORMAL;
}

If you need to try it out for yourself here is the link to the github repo

  • al4s@feddit.de
    link
    fedilink
    arrow-up
    4
    ·
    9 months ago

    player_hand and dealer_hand are only [DECK_SIZE/2] in length, but in initialize_decks you write zeros into them unti [DECK_SIZE -1]. Since the arrays are located next to each other in memory you end up overwriting the deck array.