12.12. Multiple Choice Exercises

Q-1: Select all of the true statements.

• You can have a vector that stores a vector of objects.

• C++ allows for a variety of different compositions.

• In order to check to see if two Cards are equal, we can use the == operator.

• We have to write a function that compares two Cards.

• There is no faster way to search through an unsorted vector than using a linear search.

• If the vector were sorted, then there are faster search methods.

• There is no such thing as an empty object.

• All variables are given default values unless otherwise specified by the user.

Q-2: What is the correct way to declare a vector of vectors of ints called vec?

• vector<int> vec;

• This declares a vector of ints.

• vector<int> vec<int>;

• This is not the proper way to declare vec.

• vector<vector<int> vec;

• Close! Look closely at the answer choices again.

• vector<vector<int> > vec;

• This is the proper way to declare a vector of vectors of ints.

Q-3: What is the value of card?

struct Card {
  int suit, rank;
  Card ();
  Card (int s, int r);
};

Card::Card () {
  suit = 0;  rank = 0;
}

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

int main() {
  Card card (2, 8);
}

• Ace of Clubs

• How did we define our mapping earlier in the chapter?

• 8 of Hearts

• card has a suit value of 2 corresponding to Hearts, and a rank value of 8.

• King of Hearts

• How did we define our mapping earlier in the chapter?

• card does not have a value.

• We initialized card with a suit value of 2 and a rank value of 8.

Q-4: There is an error with the code below. Can you find it?

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

int main() {
  Card card (1,3);
  print (card);
}

• card is not a valid Card.

• A suit of 1 and a rank of 3 maps to the 3 of Diamonds.

• There shouldn’t be a semicolon after the struct definition.

• A struct definition always ends with a semicolon.

• print is a member function.

• Since print is a member function, we need to use the dot operator.

• There is nothing wrong with the code.

• There is an error with the code. Can you find it?

Q-5: What is the output of the code below?

struct Card {
  int suit, rank;
  Card ();
  Card (int s, int r);
  void print () const;
  bool isGreater (const Card& c2) const;
};

int main() {
  Card card1 (2,12);
  Card card2 (2,2);
  cout << card1.isGreater (card2) << endl;
}

• True

• The output of a bool is either a 0 or 1.

• False

• The output of a bool is either a 0 or 1.

• 0

• Is card1 greater than card2?

• 1

• The Queen of Hearts is greater than the 2 of Hearts.

Q-6: What is the output of the code below?

struct Card {
  int suit, rank;
  Card ();
  Card (int s, int r);
  void print () const;
  bool isGreater (const Card& c2) const;
};

vector<Card> buildDeck();

bool equals (const Card& c1, const Card& c2){
  return (c1.rank == c2.rank && c1.suit == c2.suit);
}

void printDeck(const vector<Card>& deck);

int find (const Card& card, const vector<Card>& deck);

int main() {
  vector<Card> deck = buildDeck();
  Card card (3, 13);
  cout << find(card, deck);
}

• 51

• The card is the King of Spades, which is located at the end of the deck.

• 52

• Since the vector is size 52, it cannot have an index of 52.

• 12

• What is the value of card?

• -1

• What is the value of card?

Q-7: What is true about deck?

struct Card {
  int suit, rank;
  Card ();
  Card (int s, int r);
  void print () const;
  bool isGreater (const Card& c2) const;
};

vector<Card> createDeck() {
  vector<Card> deck (12);
  int i = 0;
  for (int suit = 0; suit <= 3; suit++) {
    for (int rank = 1; rank < 4; rank++) {
      deck[i].suit = suit;
      deck[i].rank = rank;
      i++;
    }
  }
  return deck;
}

int main() {
  vector<Card> deck = createDeck();
}

• It contains 12 Cards.

• createDeck returns a vector of size 12, corresponding to 12 Cards.

• The highest rank is 4.

• The rank goes up to but does not include 4.

• There are no spades in the deck.

• The suit goes up to and include the suit value 3 which corresponds to spades.

• The deck has 3 cards in each suit.

• Each suit has an Ace, 2, and 3.

Q-8: How many times does findBisect need to call itself in order to find the King of Diamonds?

struct Card {
  int suit, rank;
  Card ();
  Card (int s, int r);
  void print () const;
  bool isGreater (const Card& c2) const;
};

vector<Card> buildDeck();
bool equals (const Card& c1, const Card& c2);
void printDeck(const vector<Card>& deck);
int find (const Card& card, const vector<Card>& deck);
int findBisect (const Card& card, const vector<Card>& deck, int low, int high);

int main() {
  vector<Card> deck = buildDeck();
  Card card (1, 13);
  cout << findBisect(card, deck, 0, 51);
}

• 0

• The King of Diamonds is right in the middle of the deck, so it doesn’t need to call itself.

• 1

• Where is the King of Diamonds located relative to the sorted deck?

• 3

• Where is the King of Diamonds located relative to the sorted deck?

• 4

• Where is the King of Diamonds located relative to the sorted deck?

Q-9: We want to write the function findAllQueens, which searches through a deck and prints out the location of all 4 queens in the deck. What should go in the blanks?

struct Card {
  int suit, rank;
  Card ();
  Card (int s, int r);
  void print () const;
  bool isGreater (const Card& c2) const;
};

vector<Card> buildDeck();
bool equals (const Card& c1, const Card& c2);
void printDeck(const vector<Card>& deck);

void findAllQueens (const vector<Card>& deck) {
  for (size_t i = 0; i < deck.____; ++i) {
    if (deck[i].____ == 12) {
      cout << ____ << " ";
    }
  }
}

int main() {
  vector<Card> deck = buildDeck();
  findAllQueens (deck);
}

• push_back(), suit, i

• What value should i go up to?

• size(), rank, i

• These are the correct variables and functions.

• size, rank, deck[i]

• We want to print the index, not the card.

• front(), suit, deck

• What value should i go up to?

Q-10: What is the process of modeling a complex system with a simplified description in order to suppress unnecessary details while capturing relevant behavior?

• Generalization

• Generalization means to take something specific and make it more general.

• Encapsulation

• Encapsulation means taking a piece of code and wrapping it up in a function.

• Abstraction

• Using this process, we can remove unnecessary details to focus on the more important aspects.

• Implementation

• Implementation is the process of taking an idea and making it real.

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