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.

sc-1-1: 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?

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

        double h = 0;
double w = 0;
---
std::cout << "Enter height:\t";
---
std::cin >> h;
---
std::cout << "Enter width:\t";
---
std::cin >> w;
---
double area = h*w;
---
std::cout << area << '\n';
        

Fix this program so that it compiles.

int main() { 21 = value; double value; std::cout << value << '\n'; }

sc-1-4: 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?

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.

        int main () {
---
  std::cout << "Odd numbers:\n";
---
  for(int num=1; num<=100; ++num) {
---
    if(num * 2 == 0) {  #distractor
---
    if(num % 2 != 0) {
---
      std::cout << '\t' << num << '\n';
---
    }
---
  }
}
        

sc-1-7: 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.

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

#include <iostream> int main() { }

sc-1-9: 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.

sc-1-10: 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.

sc-1-11: 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.

sc-1-12: 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?

sc-1-13: 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)

sc-1-14: Given the following statement:

double x = 2 + 2^3

What is value stored in x?

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