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How To Think Like a Computer Scientist C++ Edition The Pretext Interactive Version

Barbara Ericson, Allen B. Downey, Jason L. Wright (Editor)

Section 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.
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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;
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Listing 13.4.1. This active code prints out the cards in a deck using the loop from the previous section.
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Checkpoint 13.4.1.

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.
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  • True - we used the buildDeck function with a few modifications to do this.
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  • How do we create the deck?
  • True - we wrote a Deck constructor to do this.
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  • 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.
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  • Look at the active code. How do we create the deck?
  • False - we wrote a Deck constructor to do this.
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  • Look at the active code.
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Checkpoint 13.4.2.

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.
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