13.4. Another constructor¶

Now that we have a Deck object, it would be useful to initialize the cards in it. From the previous chapter we have a function called buildDeck that we could use (with a few adaptations), but it might be more natural to write a second Deck constructor.

Deck::Deck () {
  vector<Card> temp (52);
  cards = temp;

  int i = 0;
  for (Suit suit = CLUBS; suit <= SPADES; suit = Suit(suit+1)) {
    for (Rank rank = ACE; rank <= KING; rank = Rank(rank+1)) {
      cards[i].suit = suit;
      cards[i].rank = rank;
      i++;
    }
  }
}

Notice how similar this function is to buildDeck, except that we had to change the syntax to make it a constructor. Now we can create a standard 52-card deck with the simple declaration Deck deck;

The active code below prints out the cards in a deck using the loop from the previous section.

#include <iostream>
#include <string>
#include <vector>
using namespace std;

enum Suit { CLUBS, DIAMONDS, HEARTS, SPADES };

enum Rank { ACE=1, TWO, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE,
TEN, JACK, QUEEN, KING };

struct Card {
    Rank rank;
    Suit suit;
    Card ();
    Card (Suit s, Rank r);
    void print () const;
};

struct Deck {
    vector<Card> cards;
    Deck ();
};

int main() {
    Deck deck;
    for (int i = 0; i < 52; i++) {
        deck.cards[i].print();
    }
}

====
Card::Card () {
    suit = SPADES;  rank = ACE;
}

Card::Card (Suit s, Rank r) {
    suit = s;  rank = r;
}

void Card::print () const {
    vector<string> suits (4);
    suits[0] = "Clubs";
    suits[1] = "Diamonds";
    suits[2] = "Hearts";
    suits[3] = "Spades";

vector<string> ranks (14);
    ranks[1] = "Ace";
    ranks[2] = "2";
    ranks[3] = "3";
    ranks[4] = "4";
    ranks[5] = "5";
    ranks[6] = "6";
    ranks[7] = "7";
    ranks[8] = "8";
    ranks[9] = "9";
    ranks[10] = "10";
    ranks[11] = "Jack";
    ranks[12] = "Queen";
    ranks[13] = "King";

cout << ranks[rank] << " of " << suits[suit] << endl;
}

Deck::Deck () {
    vector<Card> temp (52);
    cards = temp;

int i = 0;
    for (Suit suit = CLUBS; suit <= SPADES; suit = Suit(suit+1)) {
        for (Rank rank = ACE; rank <= KING; rank = Rank(rank+1)) {
            cards[i].suit = suit;
            cards[i].rank = rank;
            i++;
        }
    }
}

Q-2: Based on your observations from the active code above, the cards in deck are initialized to the correct suits and ranks of a standard deck of 52 cards.

True - we used the buildDeck function with a few modifications to do this.
How do we create the deck?
True - we wrote a Deck constructor to do this.
The for loops in the Deck constructor initialize each card to its proper value.
False - we used the buildDeck function with a few modifications to do this.
Look at the active code. How do we create the deck?
False - we wrote a Deck constructor to do this.
Look at the active code.

Let’s write a constructor for a deck of cards that uses 40 cards. This deck uses all 4 suits and ranks Ace through 10, omitting all face cards.

        Deck::Deck () {
---
   vector temp (40);
---
   vector temp (52);                         #paired
---
   cards = temp;
   int i = 0;
---
   for (Suit suit = CLUBS; suit <= SPADES; suit = Suit(suit+1)) {
---
   for (Suit suit = CLUBS; suit < SPADES; suit = Suit(suit+1)) {                         #paired
---
      for (Rank rank = ACE; rank <= TEN; rank = Rank(rank+1)) {
---
      for (Rank rank = ACE; rank <= KING; rank = Rank(rank+1)) {                         #paired
---
        cards[i].suit = suit;
        cards[i].rank = rank;
---
        cards[i].suit = rank;
        cards[i].rank = suit;                         #paired
---
        i++;
      }
   }
}

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