Question

Im learning basic C on my own and trying to create a poker client. I have an array with cards (called kortArray) and a players hand (called kortHand). My implementation does not shuffle the deck, but add all 52 cards in sequence and then randomly selecting 5 cards from the deck. I’ve added a flag (called draget) which tells if a card has been picked up befor or not.

Now, when I run the algorithm below, it usually generates five random numbers which makes the player’s or computer’s hand. But sometimes it generates less then five numbers, even though I’ve specifically stated to generate five accepted values.

I have two loops, one that runs five times, and the other is nested and runs until it finds a card which hasn’t yet been picked. The printf in the middle tells me that this algorithm doesn’t always generate five accepted numbers, and when that happens the player’s hand contains cards with nonsense-values.

srand((unsigned)(time(0)));
for(i = 0; i < 5; i++) {                        
    int x = rand()%52 + 1;
    while (kortArray[x].draget!=1) {                
        x = rand()%52 + 1;
        if (kortArray[x].draget != 1) {
            printf("%i\n", x);
            kortArray[x].draget = 1;
            kortHand[i] = kortArray[x];
        }
    }
}

Answer 1

The problem still lies in the +1 for the random numbers.

Also, you are first checking in the the first assignment to x if the card is already picked, and than you assign it to an other card.

Why not use something like:

int nr_cards_picked = 0             /* Number of uniquely picked cards in hand */
/* Continue picking cards until 5 unique cards are picked. */
while (nr_cards_picked < 5) {
    x = rand() % 52;                         /* Take a random card */
    if (kortArray[x].draget == 0) {
        /* Pick this card. */
        kortArray[x].draget = 1;             /* Card is picked */
        kortHand[i]         = kortArray[x];  /* Add picked card to hand */
        nr_cards_picked++;
    }
}

Forgive compiler errors; I don’t have a compiler near here.

This case you only have one time a random number call.

Theoretically it might never end but this is not likely.