Wrap-Up

Answers to Self Review Exercises

2.1

a) main. b) left brace ({), right brace (}). c) semicolon. d) newline. e) if.
2.2
  1. False. Comments do not cause any action to be performed when the program is executed. They are used to document programs and improve their readability.

  2. True.

  3. True.

  4. True.

  5. False. C++ is case sensitive, so these variables are unique.

  6. True.

  7. True.

  8. False. The operators *, / and % have the same precedence, and the operators + and - have a lower precedence.

  9. False. A single cout statement with multiple escape sequences can print several lines.
2.3
  1. int c, thisIsAVariable, q76354, number;

  2. std::cout << "Enter an integer: ";

  3. std::cin >> age;

  4. if ( number != 7 ) std::cout << "The variable number is not equal to 7 ";

  5. std::cout << "This is a C++ program ";

  6. std::cout << "This is a C++ program ";

  7. std::cout << "This is a C++ program ";

  8. std::cout << "This is a C++ program ";
 
2.4
  1. // Calculate the product of three integers

  2. int x; int y; int z; int result;

  3. cout << "Enter three integers: ";

  4. cin >> x >> y >> z;

  5. result = x * y * z;

  6. cout << "The product is " << result << endl;

  7. return 0;
2.5

(See program below)

1 // Calculate the product of three integers 2 #include // allows program to perform input and output 3 4 using std::cout; // program uses cout 5 using std::cin; // program uses cin 6 using std::endl; // program uses endl 7 8 // function main begins program execution 9 int main() 10 { 11 int x; // first integer to multiply 12 int y; // second integer to multiply 13 int z; // third integer to multiply 14 int result; // the product of the three integers 15 16 cout << "Enter three integers: "; // prompt user for data 17 cin >> x >> y >> z; // read three integers from user 18 result = x * y * z; // multiply the three integers; store result 19 cout << "The product is " << result << endl; // print result; end line 20 21 return 0; // indicate program executed successfully 22 } // end function main

2.6
  1. Error: Semicolon after the right parenthesis of the condition in the if statement.

    Correction: Remove the semicolon after the right parenthesis. [Note: The result of this error is that the output statement will be executed whether or not the condition in the if statement is true.] The semicolon after the right parenthesis is a null (or empty) statementa statement that does nothing. We will learn more about the null statement in the next chapter.

  2. Error: The relational operator =>.

    Correction: Change => to >=, and you may want to change "equal to or greater than" to "greater than or equal to" as well.

Exercises

2.7

Discuss the meaning of each of the following objects:

  1. std::cin

  2. std::cout
2.8

Fill in the blanks in each of the following:

  1. ______ are used to document a program and improve its readability.

  2. The object used to print information on the screen is _____.

  3. A C++ statement that makes a decision is ______.

  4. Most calculations are normally performed by ______ statements.

  5. The ______ object inputs values from the keyboard.
2.9

Write a single C++ statement or line that accomplishes each of the following:

  1. Print the message "Enter two numbers".

  2. Assign the product of variables b and c to variable a.

  3. State that a program performs a payroll calculation (i.e., use text that helps to document a program).

  4. Input three integer values from the keyboard into integer variables a, b and c.
2.10

State which of the following are true and which are false. If false, explain your answers.

  1. C++ operators are evaluated from left to right.

  2. The following are all valid variable names: _under_bar_, m928134, t5, j7, her_sales, his_account_total, a, b, c, z, z2.

  3. The statement cout << "a = 5;"; is a typical example of an assignment statement.

  4. A valid C++ arithmetic expression with no parentheses is evaluated from left to right.

  5. The following are all invalid variable names: 3g, 87, 67h2, h22, 2h.
2.11

Fill in the blanks in each of the following:

  1. What arithmetic operations are on the same level of precedence as multiplication? ______.

  2. When parentheses are nested, which set of parentheses is evaluated first in an arithmetic expression? ______.

  3. A location in the computer's memory that may contain different values at various times throughout the execution of a program is called a ______.
2.12

What, if anything, prints when each of the following C++ statements is performed? If nothing prints, then answer "nothing." Assume x = 2 and y = 3.

  1. cout << x;

  2. cout << x + x;

  3. cout << "x=";

  4. cout << "x = " << x;

  5. cout << x + y << " = " << y + x;

  6. z = x + y;

  7. cin >> x >> y;

  8. // cout << "x + y = " << x + y;

  9. cout << " ";
2.13

Which of the following C++ statements contain variables whose values are replaced?

  1. cin >> b >> c >> d >> e >> f;

  2. p = i + j + k + 7;

  3. cout << "variables whose values are replaced";

  4. cout << "a = 5";
2.14

Given the algebraic equation y = ax3 + 7, which of the following, if any, are correct C++ statements for this equation?

  1. y = a * x * x * x + 7;

  2. y = a * x * x * ( x + 7 );

  3. y = ( a * x ) * x * ( x + 7 );

  4. y = (a * x) * x * x + 7;

  5. y = a * ( x * x * x ) + 7;

  6. y = a * x * ( x * x + 7 );
 
2.15

State the order of evaluation of the operators in each of the following C++ statements and show the value of x after each statement is performed.

  1. x = 7 + 3 * 6 / 2 - 1;

  2. x = 2 % 2 + 2 * 2 - 2 / 2;

  3. x = ( 3 * 9 * ( 3 + ( 9 * 3 / ( 3 ) ) ) );
2.16

Write a program that asks the user to enter two numbers, obtains the two numbers from the user and prints the sum, product, difference, and quotient of the two numbers.
2.17

Write a program that prints the numbers 1 to 4 on the same line with each pair of adjacent numbers separated by one space. Do this several ways:

  1. Using one statement with one stream insertion operator.

  2. Using one statement with four stream insertion operators.

  3. Using four statements.
2.18

Write a program that asks the user to enter two integers, obtains the numbers from the user, then prints the larger number followed by the words "is larger." If the numbers are equal, print the message "These numbers are equal."
2.19

Write a program that inputs three integers from the keyboard and prints the sum, average, product, smallest and largest of these numbers. The screen dialog should appear as follows:

Input three different integers: 13 27 14 Sum is 54 Average is 18 Product is 4914 Smallest is 13 Largest is 27  

2.20

Write a program that reads in the radius of a circle as an integer and prints the circle's diameter, circumference and area. Use the constant value 3.14159 for p. Do all calculations in output statements. [Note: In this chapter, we have discussed only integer constants and variables. In Chapter 4 we discuss floating-point numbers, i.e., values that can have decimal points.]
2.21

Write a program that prints a box, an oval, an arrow and a diamond as follows:

********* *** * * * * * * *** * * * * * * ***** * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ********* *** * *  

2.22

What does the following code print?

cout << "* ** *** **** *****" << endl;

2.23

Write a program that reads in five integers and determines and prints the largest and the smallest integers in the group. Use only the programming techniques you learned in this chapter.
2.24

Write a program that reads an integer and determines and prints whether it is odd or even. [Hint: Use the modulus operator. An even number is a multiple of two. Any multiple of two leaves a remainder of zero when divided by 2.]
 
2.25

Write a program that reads in two integers and determines and prints if the first is a multiple of the second. [Hint: Use the modulus operator.]
2.26

Display the following checkerboard pattern with eight output statements, then display the same pattern using as few statements as possible.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *  

2.27

Here is a peek ahead. In this chapter you learned about integers and the type int. C++ can also represent uppercase letters, lowercase letters and a considerable variety of special symbols. C++ uses small integers internally to represent each different character. The set of characters a computer uses and the corresponding integer representations for those characters is called that computer's character set. You can print a character by enclosing that character in single quotes, as with

cout << 'A'; // print an uppercase A  

You can print the integer equivalent of a character using static_cast as follows:

cout << static_cast< int >( 'A' ); // print 'A' as an integer  

This is called a cast operation (we formally introduce casts in Chapter 4). When the preceding statement executes, it prints the value 65 (on systems that use the ASCII character set). Write a program that prints the integer equivalent of a character typed at the keyboard. Test your program several times using uppercase letters, lowercase letters, digits and special characters (like $).
2.28

Write a program that inputs a five-digit integer, separates the integer into its individual digits and prints the digits separated from one another by three spaces each. [Hint: Use the integer division and modulus operators.] For example, if the user types in 42339, the program should print:

4 2 3 3 9  

2.29

Using only the techniques you learned in this chapter, write a program that calculates the squares and cubes of the integers from 0 to 10 and uses tabs to print the following neatly formatted table of values:

integer square cube 0 0 0 1 1 1 2 4 8 3 9 27 4 16 64 5 25 125 6 36 216 7 49 343 8 64 512 9 81 729 10 100 1000  

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