CODEWITHSUNDEEP
c
tyson
tyson

Reputation: 53

C -- Trouble with initializing dynamic list

I'm having trouble with the deal function in a blackjack program I am writing. Can anyone see what is going on? When I try to print in main(), I get a segmentation fault.

Cheers.

MAIN FUNCTION

int main(void)
{
    int i, j, k, purse;
    card deck[52];
    card *head_d, *temp_d, *current_d = NULL, *last_d, *head_p, *temp_p, *current_p = NULL, *last_p;



make(deck);  //CREATES THE DECK
shuffle(deck); //SHUFFLES THE DECK
deal(deck, head_d, current_d, head_p, current_p)

for(i = 0; i < DECK_SIZE; i++)
    {
        printf("%d: %d %c\n", i + 1, deck[i].face, deck[i].suit);
    }

temp_p = head_p;
while(temp_p != NULL)
{
printf("%d %c\n", temp_p->face, temp_p->suit);
temp_p = temp_p->listp;
}

return(0);
}

FUNCTION deal()

  void deal(card x[DECK_SIZE], card *head_d, card *current_d, card *head_p, card *current_p)
    {

    int i;
    card *temp_p, *temp_d;

    for(i = 0; i < 4; i++)
    {
        if( i % 2 == 0)
        {
            temp_p = (card *)malloc(sizeof(card));
            temp_p->face = x[i].face;
            temp_p->suit = x[i].suit;

            if (current_p==NULL)
            {
                head_p=temp_p;
            }
            else
            {
                current_p->listp=temp_p;
            }
                current_p = temp_p;
                temp_p->listp = NULL;

        }
        else
        {
            temp_d=(card *)malloc(sizeof(card));
            temp_d->face = x[i].face;
            temp_d->suit = x[i].suit;

            if (current_d==NULL)
            {
                head_d=temp_d;
            }
            else
            {
                current_d->listp=temp_d;
            }
                current_d = temp_d;
                temp_d->listp = NULL;
        }
    }
}

Upvotes: 2

Views: 99

Answers (2)

Some programmer dude
Some programmer dude

Reputation: 409166

The problem is that the arguments to the deal function is local, meaning when you change their value in the function, the variables used when calling the function will not be changed. You need to pass those arguments by reference:

void deal(card x[DECK_SIZE], card **head_d, card **current_d, card **head_p, card **current_p);

The do e.g.

*head_p=temp_p;

in the function to set the variables.

Call as

deal(deck, &head_d, &current_d, &head_p, &current_p);

Upvotes: 2

AnT stands with Russia
AnT stands with Russia

Reputation: 320391

You have uninitialized pointer variable head_p in your main function. Yet you are attempting to read data supposedly pointed by head_p. Of course, you will get segfault.

Upvotes: 0

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