Thread: Card game, having a problem with strings.

In the shuffleDeck function, I'm printing out "cards" in the while loop and I'm getting junk after some of the strings along with a segfault at the bottom of the list. I tried using realloc, in order to reallocate the string to the size of the new string being copied to it, but that didn't do it. Any help? Thanks.

Code:

void setCards(char **cards){ 
    char *suit[SUIT_MAX] = {"Clubs", "Diamonds", "Hearts", "Spades"};
    char *rank[RANK_MAX] = {"Ace", "2", "3", "4", "5", "6", 
        "7", "8", "9", "10", "Jack", "Queen", "King"};


    int rankIdx, suitIdx, cardIdx;
    for(suitIdx = 0; suitIdx < SUIT_MAX; suitIdx++){
        for(rankIdx = 0; rankIdx < RANK_MAX; rankIdx++){
            cardIdx = suitIdx * RANK_MAX + rankIdx;
            cards[cardIdx] = malloc(strlen(suit[suitIdx]) + strlen(rank[rankIdx]) + 4);
            sprintf(cards[cardIdx], "%s of %s", rank[rankIdx], suit[suitIdx]);
            cards[cardIdx][strlen(cards[cardIdx])] = '\0';
        }
    }


}


void shuffleDeck(char **cards){
    int cardIdx = RANK_MAX * SUIT_MAX;
    char *temp;
    while(cardIdx > 1){
        int random = rand() % cardIdx;
        cardIdx--;
        temp = malloc(strlen(cards[cardIdx]));
        strcpy(temp, cards[cardIdx]);
        temp[strlen(temp)] = '\0';
        cards[cardIdx] = realloc(cards[cardIdx], strlen(cards[random])); <-- ??
        strcpy(cards[cardIdx], cards[random]);
        strcpy(cards[random], temp);
        free(temp);
        puts(cards[cardIdx]);
    }


}

You're not leaving any room for the terminating '\0' when you allocate memory. The last part of this statement should be at least +5, but a bit more won't hurt:

Code:

    cards[cardIdx] = malloc(strlen(suit[suitIdx]) + strlen(rank[rankIdx]) + 8);

All this does is store a '\0' where strlen() already found a '\0'.

Code:

    cards[cardIdx][strlen(cards[cardIdx])] = '\0';

Your main problem is that you need to add 5 not 4 in this line, since you need one extra for the zero-terminator:

Code:

cards[cardIdx] = malloc(strlen(suit[suitIdx]) + strlen(rank[rankIdx]) + 4);

Since sprintf will ensure the string is zero-terminated, you don't need this line:

Code:

cards[cardIdx][strlen(cards[cardIdx])] = '\0';

shuffleDeck can be simplified by just swapping the pointers.

Code:

void shuffleDeck(char **cards){
    int cardIdx = RANK_MAX * SUIT_MAX;
    char *temp;
    while(cardIdx > 1){
        int random = rand() % cardIdx;
        cardIdx--;
        temp = cards[cardIdx];
        cards[cardIdx] = cards[random];
        cards[random] = temp;
        puts(cards[cardIdx]);
    } 
}

EDIT: That rcgldr is quick!

*Smacks forehead*

Thank you both, good suggestion ooga!