11.10. Multiple Choice Exercises

Answer the following Multiple Choice questions to assess what you have learned in this chapter.

Q-1: Suppose you are randomly assigning students to discussions 1-8. How would you do this correctly? Assume you have alreay implemented the following code.

int x = random ();

• int y = x % 7;
  y = y + 1;
  

• The first part creates a random number between 0 and 7 (8 numbers) and the second part adds 1 so that our random number is actually between 1 and 8.

• int y = x % 8;
  y = y + 1;
  

• The first part creates a random number between 0 and 8 (9 numbers). This is too many.

• int y = x % 7;
  

• This creates a random number between 0 and 7 (8 numbers), which are not the numbers we are looking for.

• int y = x % 8;
  

• The first part creates a random number between 0 and 8 (9 numbers). This is too many, and not the numbers we are looking for.

Q-2: Suppose you have defined the fizzBuzz function as the following

int fizzBuzz (const vector<int> & vec, int num1, int num2) {
    int count = 0;
    for (size_t i = 0; i < vec.size(); i++) {
        if (vec[i]/num1 == 0 && vec[i]/num2 == 0) {
            count++;
        }
    }
    return count;
}

What would be printed in the following case?

vector<int> numbers = {6, 8, 14, 21, 28, 35, 36, 42, 49, 70, 81, 98};
cout << fizzBuzz(numbers, 2, 7);

• 1

• 14 is 7 * 2. Don’t forget about the other multiples of 7 and 2.

• 2

• See if you can find the other multiples of 7 and 2.

• 3

• See if you can find the other multiples of 7 and 2.

• 4

• See if you can find the other multiples of 7 and 2.

• 5

• 14, 28, 42, 70, and 98 are all multiples of 7 and 2 and are counted by fizzBuzz.

Q-3: Suppose you have defined the startsWith function as the following

int startsWith (const vector<string> & vec, char c) {
    int count = 0;
    int pos = 0;
    for (size_t i = 0; i < vec.size(); i++) {
        pos = vec[i].find(" ");
        if (vec[i][pos + 1] == c) {
            count++;
        }
    }
    return count;
}

What would be printed in the following case?

vector<string> names = {"Ross Meldrum", "Monica Morrissey", "Maria Geller", "Marty Bing"};
cout << howMany(names, 'M');

• 1

• Is the function counting how many first and last names begin with "M"?

• 2

• The function is counting how many last names begin with "M".

• 3

• Is the function counting how many first names begin with "M"?

• 4

• Is the function counting how many elements in names contain "M"?

• 5

• Is the function counting how many times "M" appears in names?

Q-4: Suppose you have defined the howMany function as the following

int howMany (const vector<string>& vec, char let) {
    int count = 0;
    for (size_t i = 0; i < vec.size(); i++) {
        for (size_t c = 0; c < vec[i].size(); c++) {
            if (vec[i][c] == let) {
                count++;
            }
        }
    }
    return count;
}

What is the value of counts after the following code is run?

vector<string> snacks = {"cheetos", "ruffles", "jalepeno chips", "oreos", "m&ms"};
vector<char> letters = {'a', 'e', 'i', 'o', 'u'};
vector<int> counts = {};
for (int i = 0; i < letters.size(); ++i) {
    counts.push_back(howMany(snacks, letters[i]));
}

• {1, 6, 2, 6, 2}

• What is being counted in counts?

• {1, 4, 1, 3, 1}

• counts isn’t a count of how many words each vowel appers in inside snacks.

• {1, 6, 1, 4, 1}

• counts contains a count of how many times each vowel appers in snacks.

• {1, 6, 2, 3, 2}

• What is being counted in counts?

• Error!

• There isn’t anything wrong with the code that would cause an error.

Q-5: Suppose you have defined the repeater function as the following

int repeater (const vector<int>& vec) {
    int count = 0;
    for (size_t i = 0; i < vec.size(); i++) {
        for (size_t j = 0; j < vec.size(); j++) {
            if ((vec[j] == vec[i]) && (i != j)) {
                count++;
            }
        }
    }
    return count;
}

What is the value of counter after the following code is run?

vector<int> vals = {1,1,3,2,2,3,3,4,5,6,7,4,4,5};
int counter = repeater(vals);

• 169

• What is being counted by repeater in each iteration of the outer loop? Definitely not everything!

• 32

• repeater does count repeats but does it consider values at the same indexes repeats?

• 18

• repeater considers the number of times each index shares a value with any of the other indices.

• 13

• repeater dosen’t simply count the number of elements.

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