Exam 3

What does this algorithm do?

100

int mysteryFunction(int number){

       return number*number;

}

squares the number that was passed in

200

int x = 5;

while (x > 0) {

    cout << x << " ";

    x--;

}

counts down from 5

300

int sum = 0;

for (int i = 1; i <= 5; i++) {

    sum += i;

}

cout << sum;

adds up numbers 1-5

400

int count = 0;

for (int i = 1; i <= 3; i++) {

    for (int j = 1; j <= 2; j++) {

        count++;

    }

}

cout << count;

prints out how many numbers are in a 2*3 grid

500

int n = 1234;

int sum = 0;

while (n > 0) {

    sum += n % 10;

    n /= 10;

}

cout << sum;

prints out the sum of the digits

Where does it end?

100

int n = 10;

while (n > 0) {

    cout << n << " ";

    n--;

loop ends at 1, not 0

200

int x = 1;

while (x < 100) {

    cout << x << " ";

    x *= 2;

}

64

300

int count = 1;

while (count != 10) {

    cout << count << " ";

    count += 2;

}

This loop is infinite.

400

for (int i = 5; i > 0; i -= 2) {

    cout << i << " ";

}

5 3 1

500

for (int i = 0; i < 10; i++) {

        if (i == 4){

            break;

        }

        cout << i << " ";

    }

0 1 2 3

For loops

100

for (int i = 0; i <= 9; i += 3){

    cout << i << " ";

}

0 3 6 9

200

Which of these creates an infinite loop?
A. for (int i = 0; i < 10; i--)
B. for (int i = 0; i < 10; i++)
C. for (int i = 10; i > 0; i--)
D. for (int i = 0; i != 10; i++)

A

300

for (int i = 0; i < 5; i++) {

    cout << i << " ";

}

cout << i;

Compilation error — i is out of scope

400

for (int i = 5; i < 0; i++) {

    cout << i << " ";

}

This loop never starts

500

for (int i = 1; i <= 3; i++) {

    for (int j = 1; j <= 2; j++) {

        cout << i << "," << j << " ";

    }

}

1,1 1,2 2,1 2,2 3,1 3,2

While Loops

100

Which of the following is the correct syntax for a while loop?
A. while (i < 10) { cout << i; }
B. while i < 10 { cout << i; }
C. while (i < 10); cout << i;
D. loop (i < 10) { cout << i; }

A

200

How many times will this loop run? 

int i = 10;

while (i < 5) {

    cout << i;

    i++;

}

0 times

300

void mystery5() {

    int x = 1;

    while (x < 30) {

        cout << x << " ";

        x *= 3;

    }

}

1 3 9 27

400

int mystery10() {

    int i = 1;

    int count = 0;

    while (i < 50) {

        i *= 2;

        count++;

    }

    return count;

}

count = 6

500

int mystery8(int n) {

    int reversed = 0;

    while (n > 0) {

        reversed = reversed * 10 + (n % 10);

        n /= 10;

    }

    return reversed;

}

this function reverses the digits of n

For vs While

100

T/F: a for loop can always be replaced with a while loop.

True

200

T/F: a while loop can always be replaced with a for loop.

True

300

What is the difference between for loops and while loops?

for loops are count based, while loops are condition based. 

400

You want to find every instance of the letter 'g' in a string. 

for loop.

500

you want to add numbers until you reach 1000.

while loop