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Tutorial 4

Variables, Constants, Arithmetic Operators, and

Assignment Statements

 

Overview

This tutorial begins with discussing the difference between variables, named constants, and literal constants. Once defined the discussion moves to how to properly define each. This includes selecting an appropriate name, data type, and initial value (for variables and named constants). In addition to defining variables and named constants, the tutorial covers how each type of data will be stored. For numeric data, the concept of type casting is covered, as well as using numeric data in calculations. After numeric data is covered, the concept of obtaining string data is covered with the use of the getline function. The tutorial concludes with the building of a console application.

 

Objectives

After completing the tutorial, the student will be able to:

 

Lecture Notes

Variables

Variables were introduced in tutorial 3 to understand how to write the code from an algorithm. However it is important to understand all the details associated with variables. Remember that there are three parts to declaring a variable in C++. First determine the name of the variable, then the data type, and finally assign an initial value to it.

The first item coded is the data type, which is set using the C++ keyword that corresponds to the data type. A list of data types available in C++ is listed in figure 4-5 on page 116. Choosing an appropriate data type is important because it determines the type of data that can be stored by the variable. If storing a person’s name, you would choose the string data type. If storing a person’s age, you would choose the short data type. Note that the short data type is chosen vs. the int or long data types. This is because the short data type stores a maximum positive value of 32767, which will more than accommodate a person’s age. If the int or long data types were chosen, they would be able to accommodate the age, however because they take up more space internally (4 bytes vs. 2 bytes), storing the age would be very inefficient.

Secondly, we state the variable name. While most C++ programmers use lower case for names, if names are more than one word then the beginning of the second word is capitalized to stand out. Remember that in most programming languages that variable names can consist of letters, numbers, and maybe an underscore, however no punctuation characters or spaces. The actual rules for naming variables in C++ are as follows:

Rules for naming variables in C++

Finally, after determining the data type and naming the variable, we assign as initial value to the variable after an equal sign. It is important to give the variable an initial value or garbage may result. The initial value assigned to a variable must be of the same type as the variable.

The entire syntax for declaring a variable in C++ would look like the following:

(Note that the variable declaration ends with a semicolon)

datatype variableName = initialValue;

An example of this is the following:

float length = 0.0;

Named Constants

A named constant is a memory location whose contents cannot change while the program is running. This is different from a variable in that the contents of a variable are permitted to change while the program is running. This is the major difference between named constants and variables. Named constants require a data type, constant name, and an initial value, similar to that of a variable. However, a named constant declaration begins with the keyword const. The syntax for declaring a named constant in C++ is as follows:

const datatype constantname = expression; (where expression would be the computed value of the constant)

Literal Constants

Unlike variables and named constants, literal constants are not memory locations. Rather, a literal constant is an item of data that can appear in a program instruction, and that can be stored in a memory location. Literal constants can have a data type that is numeric, character, or string. You typically initialize a memory location by assigning a literal constant to it.

A numeric literal constant is simply a number. Numeric literals can consist of numbers, a plus sign, a minus sign, a decimal point, and the letter e in uppercase or lowercase representing exponential notation. Numeric literal constants cannot contain a space, comma, or special characters such as a dollar sign or percent sign.

A character literal constant is a single character enclosed in single quotation marks. Character literal constants store data that could be stored in a char variable type. Please note that if you wish to store more than one character, you would not use a character literal constant, but would use a string literal constant.

A string literal constant is zero or more characters enclosed in double quotation marks. To avoid the possibility of a string variable initially containing garbage, many times a string variable is initialized to the empty string. The empty string is two double quotation marks side-by-side with no space between them. By initializing a string variable to the empty string, the programmer will have more predictable results and debugging will be made easier if necessary.

Implicit type conversion

When a program instructs the computer to initialize a memory location, the computer first compares the data type of the value assigned to the memory location with the with the data type of the memory location itself to verify that the value is appropriate for the memory location. If the value’s data type does not match that of the memory location’s data type, most programming languages use a process call implicit type conversion to convert the value to fit the memory location. However it is not always possible to convert a value to match the memory location’s data type. For example, using a string literal constant to initialize a memory location that can store only integers will produce an error during the compiling phase, because the compiler cannot convert a string literal constant to an integer.

Be aware that the C++ compiler might display the warning message ‘initializing’: truncation from ‘const double’ to ‘float’ when you initialize a float memory location to a number other than 0.0. This warning message appears because Visual C++ treats all numeric literal constants containing a decimal place as a double data type. When you assign a double number (which requires 8 bytes of memory – see chart on page 116) to a float memory location (which can only store 4 bytes – see chart on page 116), Visual C++ warns you that it may need to truncate part of the number in order to store it in the memory location. To avoid this warning message, a process called type casting can be used.

Type casting

Type casting (explicit type conversion) is the process of converting data from one type to another. You typecast an item of data by enclosing the data in parentheses, and then preceding it with the C++ keyword that represents the desired data type. The following example would type cast the double number 5.1 to a float data type: float(5.1).

Note that it is also possible to type cast an existing variable. However in doing so, the data stored within the variable is temporarily type cast to the desired data type, not permanently converted. For example in the statement salary = (float)money; pretend a variable called salary has already been declared to be of the type float, and the variable money has already been declared to be of the type int. Even though we need to convert (type cast) the value in money to be of the float type before storing it in the salary variable, we do not wish to change the type of the money variable. Therefore during the statement, the value stored in the money variable will be temporarily converted to the float type and stored in the salary variable, however after the statement is complete the money variable will contain the same int type data as before.

Assignment statement

The format of the assignment statement in C++ is variablename = expression. When an assignment statement is encountered in a program, the computer assigns the value (or outcome) of the expression appearing on the right hand side of the assignment operator (=) to the variable whose variablename appears on the left hand side of the assignment operator. The expression can include literal constants, named constants, variables, arithmetic operators, and functions. The value (or outcome) of the expression must match the data type of the variable to which it is assigned. C++ will attempt implicit type conversion, however like with initializing variables, it may be necessary to perform type casting when assigning values to variables.

It is important to note that a variable may only store one piece of data at a time. Therefore once a variable has been assigned one value, and you assign another one to it, the new value replaces the original value.

Arithmetic operations

Most programs require the computer to perform one or more arithmetic calculations. The computer is instructed to perform a calculation by writing an arithmetic expression that contains one or more arithmetic operators. As you can see in figure 4-15 on page 127, each arithmetic operator is associated with a precedence number, which controls the order in which the operation is performed in an expression. Note that you can always use parentheses, which override the normal order of precedence, because parentheses have the highest precedence of the operators.

If there is an occasion in an arithmetic expression in which two operators have the same priority, the leftmost operation will be performed first. When dealing with addition and multiplication the outcome will produce the same result, however with division the results may or may not be the same. For example take the arithmetic expression 4 / 2 / 4. If the first division is performed first (4 / 2), then that result (2.0) is divided by 4, the final result would be 0.5. Where, on the other hand, if the second division were executed first (2 / 4), then 4 were divided by that result (0.5), the final result would be 8.0. You can see that in this particular case the outcome is totally different. This is why it is important to understand that parentheses may help you formulated your equations properly.

The one operator that may be new to you would be the % (or modulus) operator. The modulus operator yields the whole number remainder of a division operation. For example if I would like to know the remainder after dividing 5 into 16, I would write the following: 16 % 5. While 5 goes into 16 three time, the remainder of the operation would be 1. Note that since the modulus operator produces a whole number (integer), you need to pay close attention to the types of variables being used and whether you need to perform any type casting of the results.

getline function

The cin stream can be used to obtain a string of characters from the keyboard. However, if the string of characters the user wishes to enter contains a space, then the cin stream will not work properly. This is due to the fact that the cin stream stops reading characters from the keyboard when a space is encountered. To obtain a string of characters from the keyboard that contains a space, the getline function can be used. The syntax for using the getline function is as follows: getline (object, variablename);

In the syntax listed above, the object currently being used is the keyboard, therefore cin is coded. (Note that in the future we could use an input file object when reading data from a file). The variablename is the name of the variable that we would like to place the data from the keyboard. An example that would read data from the keyboard into the variable address would be as follows: getline(cin,address);

Creating a console application

Beginning of page 141 of your textbook the author begins the process of creating a console application. Please follow along with this example on your computer. Be sure that you understand the terminology involved. Terms that you should understand at the end of this example would be project, workspace, source file, as well as the relationship between them.

 

Discussion Topics

Additional Activities (Optional)

 

Technical Review

  

Solutions to Questions

1. c a memory location whose value can change 9. b a space enclosed in single

while the program is running quotation marks

2. d all of the above 10. c float rate = 0.0;

3. a int numItems = 0; 11. d all of the above

4. c amt_Sold 12. d none of the above

5. a float 13. b const float RATE = float(16.5);

6. c numeric 14. d 15

7. b initial = ‘H’; 15. b 6

8. c the number 0 16. d none of the above (6.0 is stored)

Solutions to Concept Lesson Exercises

  1. float price = 0.0;
  2. price = float(16.23);

  3. float height = 0.0;
  4. float width = 0.0;

    height = float(4.5);

    width = float(6.9);

  5. int population = 0;
  6. population = 60000;

  7. char letter = ‘ ’;
  8. letter = ‘A’;

  9. const float TAXRATE = float(.15);
  10. const int MAXPAY = 20;
  11. const char INSURED = ‘Y’;
  12. const string PROMPT = "Press any key to continue";
  13. int beginStock = 0;
  14. int purchased = 0;

    int sold = 0;

    int endStock = 0;

    endStock = beginStock + purchased – sold;

  15. (memory location names may vary)
  16. float sales = 0.0;

    float bonus = 0.0;

    const float RATE = float(.05);

    bonus = sales * RATE;

  17. (memory location names may vary)
  18. string name = "";

    int hours = 0;

    int payRate = 0;

    int gross = 0;

    gross = hours * payRate;

  19. d. The number 57, which is the ASCII code for the character 9, appears in the DOS window.
  20. e. The compiler issues an error message.

  21. In this exercise, the student discovers his or her system’s memory requirements (in bytes) for each of the C++ data types listed in the lesson’s Figure 4-5. Sample memory requirements are:

char 1

short 2

int 4

long 4

float 4

double 8

long double 8

boolean 1

 

14.

//T4ConE14.cpp - displays the total purchase price

#include <iostream>

using namespace std;

int main()

{

//declare variables

float numCds = 0.0;

float cdPrice = 0.0;

float totalPrice = 0.0;

//get user's input

cout << "Number of CDs purchased: ";

cin >> numCds;

cout << "CD price: ";

cin >> cdPrice;

//calculate total price

totalPrice = numCds * cdPrice;

//display total price

cout << "Total price: " << totalPrice << endl;

return 0;

} //end of main function

 

Solutions to Application Lesson Exercises

  1. getline(cin, company);
  2. getline(cin, bookTitle);
  3. tax = taxRate * grossPay;
  4. totalPrice = numItems * price;

 5.a.

Input

Processing

Output

sales

rate (.05)

Processing items: none

Algorithm:

  1. enter the sales
  2. calculate the bonus by multiplying the sales by the rate
  3. display the bonus

bonus

b.

sales

rate

bonus

330.50

.05

16.525

d.

sales

RATE

bonus

0.0

330.50

.05

0.0

16.525

//T4AppE05.cpp - displays a bonus

#include <iostream>

using namespace std;

int main()

{

//declare named constant and variables

const float RATE = float(.05);

float sales = 0.0;

float bonus = 0.0;

//enter input item

cout << "Enter sales: ";

cin >> sales;

//calculate bonus

bonus = sales * RATE;

//display bonus

cout << "Bonus: " << bonus << endl;

return 0;

} //end of main function

 

6.

a.

Input

Processing

Output

number

Processing items: none

Algorithm:

  1. enter the number
  2. calculate the number squared by multiplying the number by itself
  3. display the number squared

number squared

b.

number

number squared

10

100

d.

number

numberSquared

0

10

0

100

//T4AppE06.cpp - displays the result of squaring a number

#include <iostream>

using namespace std;

int main()

{

//declare variables

int number = 0;

int numberSquared = 0;

//enter input item

cout << "Enter number: ";

cin >> number;

//calculate number squared

numberSquared = number * number;

//display number squared

cout << "Number squared: " << numberSquared << endl;

return 0;

} //end of main function

 

 7.

a.

Input

Processing

Output

diameter

price per foot

pi (3.141593)

Processing items: none

Algorithm:

  1. enter the diameter and price per foot
  2. calculate the circumference by multiplying the diameter by pi
  3. calculate the total price by multiplying the circumference by the price per foot
  4. display the circumference and total price

circumference

total price

b.

diameter

price per foot

pi

circumference

total price

36.5

2.35

3.141593

114.668

269.47

d.

diameter

pricePerFoot

PI

circumference

totalPrice

0.0

36.5

0.0

2.35

3.141593

0.0

114.668

0.0

269.47

//T4AppE07.cpp - displays the circumference and total price

#include <iostream>

using namespace std;

int main()

{

//declare named constant and variables

float PI = float(3.141593);

float diameter = 0.0;

float pricePerFoot = 0.0;

float circumference = 0.0;

float totalPrice = 0.0;

//enter input items

cout << "Enter the diameter (in feet): ";

cin >> diameter;

cout << "Enter the price per foot: ";

cin >> pricePerFoot;

//calculate circumference and total price

circumference = diameter * PI;

totalPrice = circumference * pricePerFoot;

//display output items

cout << "Circumference: " << circumference << endl;

cout << "Total price: " << totalPrice << endl;

return 0;

} //end of main function

 

8.

a.

Input

Processing

Output

begin amount

number purchased

number sold

Processing items: none

Algorithm:

  1. enter the begin amount, number purchased, and number sold
  2. calculate the end amount by adding the number purchased to the begin amount, and then subtracting the number sold
  3. display the end amount

end amount

b.

begin amount

number purchased

number sold

end amount

5000

1000

3500

2500

d.

begin

purchased

sold

end

0

5000

0

1000

0

3500

0

2500

//T4AppE08.cpp - displays the number of dishwashers in stock at the end of the month

#include <iostream>

using namespace std;

int main()

{

//declare variables

int begin = 0;

int purchased = 0;

int sold = 0;

int end = 0;

//enter input items

cout << "Enter the beginning amount: ";

cin >> begin;

cout << "Enter the number purchased: ";

cin >> purchased;

cout << "Enter the number sold: ";

cin >> sold;

//calculate the ending amount

end = begin + purchased - sold;

//display ending amount

cout << "Ending amount: " << end << endl;

return 0;

} //end of main function

 

9.

a.

Input

Processing

Output

length

width

price per foot

Processing items: none

Algorithm:

  1. enter the length, width, and price per foot
  2. calculate the area by multiplying the length by the width
  3. calculate the total price by multiplying the area by the price per foot
  4. display the area and total price

area

total price

b.

length

width

price per foot

area

total price

12.5

14.5

3.10

181.25

561.875

d.

length

width

pricePerFoot

area

totalPrice

0.0

12.5

0.0

14.5

0.0

3.10

0.0

181.25

0.0

561.875

//T4AppE09.cpp - displays the area and total price

#include <iostream>

using namespace std;

int main()

{

//declare variables

float length = 0.0;

float width = 0.0;

float pricePerFoot = 0.0;

float area = 0.0;

float totalPrice = 0.0;

//enter input items

cout << "Enter the length: ";

cin >> length;

cout << "Enter the width: ";

cin >> width;

cout << "Enter the price per foot: ";

cin >> pricePerFoot;

//calculate the area and total price

area = length * width;

totalPrice = area * pricePerFoot;

//display output items

cout << "Area: " << area << endl;

cout << "Total Price: " << totalPrice << endl;

return 0;

} //end of main function

10.

a.

Input

Processing

Output

length

width

depth

Processing items: none

Algorithm:

  1. enter the length, width, and depth
  2. calculate the volume by multiplying the length by the width, and then multiplying the result by the depth
  3. display the volume

volume

b.

length

width

depth

volume

100

30.5

4

12200

d.

length

width

depth

volume

0.0

100

0.0

30.5

0.0

4

0.0

12200

//T4AppE10.cpp - displays the volume of a rectangular pool

#include <iostream>

using namespace std;

int main()

{

//declare variables

float length = 0.0;

float width = 0.0;

float depth = 0.0;

float volume = 0.0;

//enter input items

cout << "Enter the length: ";

cin >> length;

cout << "Enter the width: ";

cin >> width;

cout << "Enter the depth: ";

cin >> depth;

//calculate the volume

volume = length * width * depth;

//display the volume

cout << "Volume: " << volume << endl;

return 0;

} //end of main function

 

 11.

a.

Input

Processing

Output

name

hours worked

Processing items: remaining hours

Algorithm:

  1. enter the name and hours worked
  2. calculate the weeks by dividing the hours worked by 40
  3. calculate the remaining hours by finding the remainder of the hours worked divided by 40
  4. calculate the number of days worked by dividing the remaining hours by 8
  5. calculate the number of hours worked by finding the remainder of the remaining hours divided by 8
  6. display the name, weeks, days, and hours

name

weeks

days

hours

b.

name

hours worked

remaining hours

weeks

days

hours

Mary Claire

Jackie Smith

Sue Jones

88

111

12

8

31

12

2

2

0

1

3

1

0

7

4

d.

name

hoursWorked

remainHours

weeks

days

hours


Mary Claire


Jackie Smith


Sue Jones

0

88

0

111

0

12

0

8

0

31

0

12

0

2

0

2

0

0

0

1

0

3

0

1

0

0

0

7

0

4

 

//T4AppE11.cpp - displays the number of weeks, days, and hours worked

#include <iostream>

#include <string>

using namespace std;

int main()

{

//declare variables

string name = "";

int hoursWorked = 0;

int remainHours = 0;

int weeks = 0;

int days = 0;

int hours = 0;

//enter input items

cout << "Enter the name: ";

getline(cin, name);

cout << "Enter the hours worked: ";

cin >> hoursWorked;

//calculate the weeks, days, and hours

weeks = hoursWorked / 40;

remainHours = hoursWorked % 40;

days = remainHours / 8;

hours = remainHours % 8;

//display the output items

cout << "Name: " << name << endl;

cout << "Weeks: " << weeks << endl;

cout << "Days: " << days << endl;

cout << "Hours: " << hours << endl;

return 0;

} //end of main function

 

 12.

a.

Input

Processing

Output

item

quantity

units per box

Processing items: none

Algorithm:

  1. enter the item, quantity, and units per box
  2. calculate the full boxes packed by dividing the quantity by the units per box
  3. calculate the remaining items by finding the remainder of the full boxes packed divided by the units per box
  4. display the item, full boxes packed, and remaining items

item

full boxes packed

remaining items

b.

item

quantity

units per box

full boxes packed

remaining items

Cleanser

Hair Spray

Comb

45

100

78

6

3

5

7

33

15

3

1

3

d.

item

quantity

unitsPerBox

fullBoxes

remainItems


Cleanser


Hair Spray


Comb

0

45

0

100

0

78

0

6

0

3

0

5

0

7

0

33

0

15

0

3

0

1

0

3

 

//T4AppE12.cpp - displays the number of full boxes that can be packed and the number of items remaining

#include <iostream>

#include <string>

using namespace std;

int main()

{

//declare variables

string item = "";

int quantity = 0;

int unitsPerBox = 0;

int fullBoxes = 0;

int remainItems = 0;

//enter input items

cout << "Enter the item name: ";

getline(cin, item);

cout << "Enter the quantity in inventory: ";

cin >> quantity;

cout << "Enter the number of items that can be packed in a box: ";

cin >> unitsPerBox;

//calculate the number of full boxes and the number of items remaining

fullBoxes = quantity / unitsPerBox;

remainItems = quantity % fullBoxes;

//display the output items

cout << "Item: " << item << endl;

cout << "Full boxes: " << fullBoxes << endl;

cout << "Items remaining: " << remainItems << endl;

return 0;

} //end of main function

 

13.

a.

Input

Processing

Output

original pennies

Processing items: leftover

Algorithm:

  1. enter the original pennies
  2. calculate the dollars by dividing the original pennies by 100
  3. calculate the leftover by finding the remainder of dividing the original pennies by 100
  4. calculate the quarters by dividing the leftover by 25
  5. calculate the leftover by finding the remainder of dividing the leftover by 25
  6. calculate the dimes by dividing the leftover by 10
  7. calculate the leftover by finding the remainder of dividing the leftover by 10
  8. calculate the nickels by dividing the leftover by 5
  9. calculate the pennies by finding the remainder of dividing the leftover by 5
  10. display the dollars, quarters, dimes, nickels, and pennies

dollars

quarters

dimes

nickels

pennies

b.

original pennies

leftover

dollars

quarters

dimes

nickels

pennies

2311

7333

11

11

1

33

8

8

23

73

0

1

1

0

0

1

1

3

d.

origPennies

leftover

dollars

quarters

dimes

nickels

pennies

0

2311

0

7333

0

11

11

1

0

33

8

8

0

23

0

73

0

0

0

1

0

1

0

0

0

0

0

1

0

1

0

3

 

//T4AppE13.cpp - displays the number of dollars, quarters, dimes, nickels, and pennies

#include <iostream>

#include <string>

using namespace std;

int main()

{

//declare variables

int origPennies = 0;

int leftover = 0;

int dollars = 0;

int quarters = 0;

int dimes = 0;

int nickels = 0;

int pennies = 0;

//enter input item

cout << "Enter the number of pennies: ";

cin >> origPennies;

//calculate the number of dollars, quarters, dimes, nickels, and pennies

dollars = origPennies / 100;

leftover = origPennies % 100;

quarters = leftover / 25;

leftover = leftover % 25;

dimes = leftover / 10;

leftover = leftover % 10;

nickels = leftover / 5;

pennies = leftover % 5;

//display the output items

cout << "Dollars: " << dollars << endl;

cout << "Quarters: " << quarters << endl;

cout << "Dimes: " << dimes << endl;

cout << "Nickels: " << nickels << endl;

cout << "Pennies: " << pennies << endl;

return 0;

} //end of main function

 

14.

a.

Input

Processing

Output

owes

paid

Processing items: leftover

Algorithm:

  1. enter the owes and paid
  2. calculate the change by subtracting the owes from the paid
  3. calculate the leftover by multiplying the change by 100
  4. calculate the dollars by dividing the leftover by 100
  5. calculate the leftover by multiplying the dollars by 100, and then subtracting the result from the leftover
  6. calculate the quarters by dividing the leftover by 25
  7. calculate the leftover by multiplying the quarters by 25, and then subtracting the result from the leftover
  8. calculate the dimes by dividing the leftover by 10
  9. calculate the leftover by multiplying the dimes by 10, and then subtracting the result from the leftover
  10. calculate the nickels by dividing the leftover by 5
  11. calculate the pennies by multiplying the nickels by 5, and then subtracting the result from the leftover
  12. display the change, dollars, quarters, dimes, nickels, and pennies

change

dollars

quarters

dimes

nickels

pennies

b.

owes

paid

leftover

change

dollars

quarters

dimes

nickels

pennies

75.34

39.67

45.55

80.00

50.00

45.55

466

66

16

6

1033

33

8

8

0

0

0

0

4.66

10.33

0

4

10

0

2

1

0

1

0

0

1

1

0

1

3

0

d.

owes

paid

leftover

change

dollars

quarters

dimes

nickels

pennies

0.0

75.34

0.0

39.67

0.0

45.55

0.0

80.00

0.0

50.00

0.0

45.55

0

466

66

16

6

0

1033

33

8

8

0

0

0

0

0

0.0

4.66

0.0

10.33

0.0

0.0

0

4

0

10

0

0

0

2

0

1

0

0

0

1

0

0

0

0

0

1

0

1

0

0

0

1

0

3

0

0

 

 

//T4AppE14.cpp - displays the change and the number of dollars, quarters, dimes, nickels, and pennies

#include <iostream>

#include <string>

using namespace std;

int main()

{

//declare variables

float owes = 0.0;

float paid = 0.0;

float change = 0.0;

int leftover = 0;

int dollars = 0;

int quarters = 0;

int dimes = 0;

int nickels = 0;

int pennies = 0;

//enter input items

cout << "Enter the amount owed: ";

cin >> owes;

cout << "Enter the amount paid: ";

cin >> paid;

//calculate the change and the number of dollars, quarters, dimes, nickels, and pennies

change = (paid - owes);

leftover = change * 100;

dollars = leftover / 100;

leftover = leftover - dollars * 100;

quarters = leftover / 25;

leftover = leftover - quarters * 25;

dimes = leftover / 10;

leftover = leftover - dimes * 10;

nickels = leftover / 5;

pennies = leftover - nickels * 5;

//display the output items

cout << "Change: " << change << endl;

cout << "Dollars: " << dollars << endl;

cout << "Quarters: " << quarters << endl;

cout << "Dimes: " << dimes << endl;

cout << "Nickels: " << nickels << endl;

cout << "Pennies: " << pennies << endl;

return 0;

} //end of main function

 

15. a. 0

    1. 1
    2. 0
    3. 1

//T4AppE15.cpp - demonstrates the bool data type

#include <iostream>

using namespace std;

int main()

{

//declare and initialize variable

bool insured = 1;

//display value in variable

cout << "The value in the insured variable is: " << insured << endl;

return 0;

} //end of main function

 

 

16. Changes made to the original code are shaded.

//T4AppE16.cpp - displays the value stored in the temp variable

#include <iostream>

using namespace std;

int main()

{

//declare and initialize variable

float temp = float(35.3);

//increase variable by 1.5

temp = temp + 1.5;

//display value in variable

cout << "After adding 1.5, the temp variable now contains "

<< temp << endl;

return 0;

} //end of main function

 

 

 17. Changes made to the original code are shaded.

//T4AppE17.cpp - displays the average sales

#include <iostream>

using namespace std;

int main()

{

//declare variables

float region1Sales = 0.0;

float region2Sales = 0.0;

float region3Sales = 0.0;

float avgSales = 0.0;

//enter input items

cout << "Enter region 1 sales: ";

cin >> region1Sales;

cout << "Enter region 2 sales: ";

cin >> region2Sales;

cout << "Enter region 3 sales: ";

cin >> region3Sales;

//calculate average sales

avgSales = (region1Sales + region2Sales + region3Sales) / 3;

//display average sales

cout << "Average sales: " << avgSales << endl;

return 0;

} //end of main function