Self Check

The questions in this section provide a chance to demonstrate your understanding of the concepts discussed so far.

After reading the material in this chapter, you should be able to answer these questions.

Given the following plain english statements:

• Create a variable x with value 8

• Create a variable y with value 5

• Add x and y, storing the result in y

If they were implemented as a program, then what value is y when finished?

Check answer

Place these statements in their proper order so that the program prompts for input, computes the area, and displays the results.

1. double area = h*w;

   ↑ ↓ ← → ✓ Use

2. double h = 0;
   double w = 0;

   ↑ ↓ ← → ✓ Use

3. std::cin >> h;

   ↑ ↓ ← → ✓ Use

4. std::cin >> w;

   ↑ ↓ ← → ✓ Use

5. std::cout << "Enter height:\t";

   ↑ ↓ ← → ✓ Use

6. std::cout << "Enter width:\t";

   ↑ ↓ ← → ✓ Use

7. std::cout << area << '\n';

   ↑ ↓ ← → ✓ Use

Check answer

Fix this program so that it compiles.

int main() {
  21 = value;
  double value;

  std::cout << value << '\n';
}

Given the following program:

int main() {
  int a = 7;
  int b = 4;

  if (a<=b) {
    a = 99;
  } else {
    int t = a;
    a = b;
    b = t;
  }
  return a;
}

What value is returned?

Check answer

Write a program that accumulates the sum of the numbers 1 - 10 and prints the result.

int main() {

}

When assembled in its proper order, the following program segment prints 'Odd numbers:' followed by all the odd numbers from 1 - 100, one per line.

1.   }
   }

   ↑ ↓ ← → ✓ Use

2. for(int num=1; num<=100; ++num) {

   ↑ ↓ ← → ✓ Use

3. if(num % 2 != 0) {

   ↑ ↓ ← → ✓ Use

4. if(num * 2 == 0) {  #distractor

   ↑ ↓ ← → ✓ Use

5. int main () {

   ↑ ↓ ← → ✓ Use

6. std::cout << "Odd numbers:\n";

   ↑ ↓ ← → ✓ Use

7. std::cout << '\t' << num << '\n';

   ↑ ↓ ← → ✓ Use

8. }

   ↑ ↓ ← → ✓ Use

Check answer

Which of the following statements represent assignment to a variable? Check all that apply.

int a;

This is a declaration

a = b;

Correct.

size_t sz = 10;

This is a declaration with initialization

cin >> a;

This may not look like an assignment, but it is.

int if = a;

Does not compile. The word 'if' is a reserved word and can't be used.

Check answer

Write a program that stores your name in a local variable and then prints it.

Write a program that prints your name

#include <iostream>

int main() {

}

Which of the following are legal variable names? Check all that apply.

int inner_product_of_a_and_b;

A ridiculously long, but valid name.

double* p2;

Correct.

char 1st_letter;

A variable may not start with a number

long large num;

A variable can't contain spaces or most special characters

long double _d;

Correct. 'long double' is a single type.

Check answer

What are the values of x, y, and z after the following code executes?

int x = 0;
int y = 1;
int z = 2;
--x;
++y;
z+=y;

x = -1, y = 1, z = 4

This code subtracts one from x, adds one to y, and then sets z to to the value in z plus the current value of y.

x = -1, y = 2, z = 3

This code subtracts one from x, adds one to y, and then sets z to to the value in z plus the current value of y.

x = -1, y = 2, z = 2

This code subtracts one from x, adds one to y, and then sets z to to the value in z plus the current value of y.

x = -1, y = 2, z = 2

This code subtracts one from x, adds one to y, and then sets z to to the value in z plus the current value of y.

x = -1, y = 2, z = 4

This code subtracts one from x, adds one to y, and then sets z to to the value in z plus the current value of y.

Check answer

What is the result of 158 % 10?

15

This would be the result of 158 divided by 10. Modulus gives you the remainder.

16

Modulus gives you the remainder after the division.

8

When you divide 158 by 10 you get a remainder of 8.

Check answer

What is the result of 3 % 8?

3

8 goes into 3 no times so the remainder is 3. The remainder of a smaller number divided by a larger number is always the smaller number!

2

This would be the remainder if the question was 8 % 3 but here we are asking for the reminder after we divide 3 by 8.

8

What is the remainder after you divide 3 by 8?

Check answer

What are the values of x, y, and z after the following code executes?

int x = 3;
int y = 5;
int z = 2;
x = z * 2;
y /= 2;
++z;

x = 6, y = 2.5, z = 2

This code sets x to z * 2 (4), y to y divided by 2 (5 / 2 = 2) and z = to z + 1 (2 + 1 = 3).

x = 4, y = 2.5, z = 2

Variable y must be an int, z is incremented

x = 4, y = 2, z = 3

Correct

x = 4, y = 2.5, z = 3

This code sets x to z * 2 (4), y must be an int

x = 6, y = 2, z = 3

This code sets x to z * 2 (4)

Check answer

Given the following statement:

double x = 2 + 2^3

What is value stored in x?

Check answer