Its a card game, I draw 2 cards from the deck (the array) with the help of two functions.

Each element of the array represent one card with a symbol Spades, Hearts, Diamonds or Clubs.

These numbers in the array \5 \4 \3 \6, represent Clubs, Dimaond, Heatrs, spades (just if ur curious)

The problem!

When I draw a card two times I sometimes get Duplicates.. The same card twice.

How do I make sure the same card cant be drawn twice? How do I avoid getting duplicates??

This is how the code Looks like.

Some INFO about the array... The further in, in the array, the higher value the element has. I have shortened the array... for easy testing of a solution... later the array will be 52 elements.

array<string, 3> cards = { "Ess \5", "Ess \4", "Ess \3" };


//The function.
pair<string, int> draw_card()
{
    int random_index = rand() % 52;
    string card = cards[random_index];
    return { card, random_index };
}

int main()
{
// Seed, random.
 srand((unsigned int)time(NULL));



// Calling the function 2 times.
    pair<string, int> you_drew = draw_card();
    cout << "You drew: " << you_drew.first << endl;

    pair<string, int> comp_drew = draw_card();
    cout << "Computer drew: " << comp_drew.first << endl;



// Deciding the winner.
    int your_score{ 0 };
    int the_computers_score{ 0 };

    if (you_drew.second > comp_drew.second) {
        cout << "You Won!" << endl;
        your_score  ;
    }
    else if (you_drew.second < comp_drew.second) {
        cout << "You Lost!" << endl;
        the_computers_score  ;
    }

        return 0;
   }

Everything is working fine, EXCEPT sometimes I get duplicates... I want to make sure I can Not get that... Somehow when I draw a card the element in the array should not be able to be drawn.. I want to avoid getting duplicates. Please help me!

Shouldnt something like this work? its not but.. shouldnt it?

pair<string, int> comp_drew = draw_card();

        if (you_drew == comp_drew) {
            bool run8 = true;
            while (run8) {
                pair<string, int> comp_drew = draw_card();


                if (comp_drew != you_drew) {
                     cout << "Computer drew: " << comp_drew.first << endl;
                    run8 = false;
                }
            }

        }

Or maybe another solution.. Perhaps after calling the function one time i can delete the return index from the array?

CodePudding user response：

You can swap the drawn card to the end and only choose an index smaller than 51 the next time.

int array_len = 52; // global variables are not great, but it's easier here
pair<string, int> draw_card()
{
    int random_index = rand() % array_len;
    --array_len;
    string card = cards[random_index];
    std::swap(cards[random_index], cards[array_len]);
    
    return { card, random_index };
}

CodePudding user response：

There are many different ways to do this.

std::random_shuffle

#include <iostream>
#include <algorithm>

using namespace std;

class CardMachine {
    static unsigned const DECK_SIZE = 4;
    int cards[DECK_SIZE] = {1,2,3,4};
    int lastUsedCardIndex = -1;
public:
    int getCard() {
        if (lastUsedCardIndex == DECK_SIZE - 1) {
            shuffle();
            lastUsedCardIndex = -1;
        }
        return cards[  lastUsedCardIndex];
    }
    
    void shuffle() {
        random_shuffle(begin(cards), end(cards));
    }
};

int main()
{
    CardMachine cardMachine = CardMachine();
    
    cout << "unhsuffled - 1,2,3,4 without duplicates:" << endl;
    cout << cardMachine.getCard() << endl;
    cout << cardMachine.getCard() << endl;
    cout << cardMachine.getCard() << endl;
    cout << cardMachine.getCard() << endl;
    
    cout << "Shuffled. Random order, and still no duplicates:" << endl;
    cardMachine.shuffle(); // or call getCard which can shuffle
    cout << cardMachine.getCard() << endl;
    cout << cardMachine.getCard() << endl;
    cout << cardMachine.getCard() << endl;
    cout << cardMachine.getCard() << endl;

    return EXIT_SUCCESS;
}

Mark Card as Taken

#include <iostream>
#include <random>

using namespace std;

class CardMachine {
    static unsigned const DECK_SIZE = 4;
    int cards[DECK_SIZE] = {1,2,3,4};
    bool cardIsGone[DECK_SIZE] = {false, false, false, false};
public:
    int getCard() {
        while(true) {
            int const RANDOM_INDEX = rand()