Programming Logic and Design, 6th Edition

Chapter 2

Exercises

1. Explain why each of the following names does or does not seem like a good variable name to you.

Answer: Answers will vary. A possible solution: a. | c | – | Valid, but probably too short to be descriptive | b. | cost | – | Good | c. | costAmount | – | Good, but redundant | d. | cost amount | – | Invalid, spaces aren’t allowed | e. | cstofdngbsns | – | Valid, but difficult to read | f. | costOfDoingBusinessThisFiscalYear | – | Valid, but long and awkward | g. | costYear2012 | – | Good | h. | 2012YearCost | – | Invalid, cannot start with a digit |
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2. If myAge and yourRate are numeric variables, and departmentName is a string variable, which of the following statements are valid assignments? If a statement is not valid, explain why not.

Answer: a. | myAge = 23 | – | Valid | b. | myAge = yourRate | – | Valid | c. | myAge = departmentName | – | Invalid, cannot assign string to numeric | d. | myAge = “departmentName” | – | Invalid, cannot assign string to numeric | e. | 42 = myAge | – | Invalid, cannot assign a value to a literal constant | f. | yourRate = 3.5 | – | Valid | g. | yourRate = myAge | – | Valid | h. | yourRate = departmentName | – | Invalid, cannot assign string to numeric | i. | 6.91 = yourRate | – | Invalid, cannot assign a value to a literal constant | j. | departmentName = Personnel | – | Invalid, literal string must be in quotes | k. | departmentName = “Personnel” | – | Valid | l. | departmentName = 413 | – | Invalid, literal string must be in quotes | m. | departmentName = “413” | – | Valid | n. | departmentName = myAge | – | Invalid, cannot assign numeric to string | o. | departmentName = yourRate | – | Invalid, cannot assign numeric to string | p. | 413 = departmentName | – | Invalid, cannot assign a value to a literal constant | q. | “413” = departmentName | – | Invalid, cannot assign a value to a literal constant |

3. Assume that cost = 10 and price = 12. What is the value of each of the following expressions?

Answer: a. | price – cost * 2 | -8 | | b. | 15 + price – 3 * 2 | 21 | | c. | (price + cost) * 3 | 66 | | d. | 4 – 3 * 2 + cost | 8 | | e. | cost * ((price – 8) + 5) + 100 | 190 | |

4. Draw a typical hierarchy chart for a paycheck-producing program. Try to think of at least 10 separate modules that might be included. For example, one module might calculate an employee’s dental insurance premium.

Answer: computeGross() printCheck() calculateCheck() getData() main() computeVoluntaryDeductions() computeMandatoryDeductions() computeDentalIns() computeMedicalIns() computeStateWithholding() computeFederalWithholding() 5. a. Draw the hierarchy chart and then plan the logic for a program for the sales manager of The Couch Potato Furniture Company. The manager needs a program to determine the profit on any item sold. Input includes the wholesale price and retail price for an item. The output is the item’s profit, which is the retail price minus the wholesale price. Use three modules. The main program declares global variables and calls housekeeping, detail, and end-of-job modules. The housekeeping module prompts for and accepts a wholesale price. The detail module prompts for and accepts the retail price, computes the profit, and displays the result. The end-of-job module displays the message “Thanks for using this program”.

Answer: A sample solution is as follows:

a. Hierarchy chart: main program housekeeping() detail() endOfJob() Flowchart:

Pseudocode:

start
Declarations
num wholesalePrice num retailPrice num profit string WHOLE_PROMPT = “Enter the wholesale price” string RETAIL_PROMPT = “Enter the retail price” string END_LINE = “Thanks for using this program” housekeeping() detail() endOfJob() stop housekeeping() output WHOLE_PROMPT input wholesalePrice return detail() output RETAIL_PROMPT input retailPrice profit = retailPrice - wholesalePrice output profit return endOfJob() output END_LINE return b. Revise the profit-determining program so that it runs continuously for any number of items. The detail loop executes continuously while the wholesale price is not 0; in addition to calculating the profit, it prompts the user for and gets the next wholesale price. The end-of-job module executes after 0 is entered for the wholesale price.

Answer: A sample solution is as follows:

b. Hierarchy chart: main program housekeeping() detailLoop() endOfJob() Flowchart:

Pseudocode:

start
Declarations
num wholesalePrice num retailPrice num profit string WHOLE_PROMPT = “Enter the wholesale price” string RETAIL_PROMPT = “Enter the retail price” string END_LINE = “Thanks for using this program” housekeeping() while not (wholesalePrice = 0) detailLoop() endwhile endOfJob() stop housekeeping() output WHOLE_PROMPT input wholesalePrice return detailLoop() output RETAIL_PROMPT input retailPrice profit = retailPrice - wholesalePrice output profit output WHOLE_PROMPT input wholesalePrice return endOfJob() output END_LINE return 6. a. Draw the hierarchy chart and then plan the logic for a program that calculates the gown size a student needs for a graduation ceremony. The program uses three modules. The first prompts a user for and accepts the student’s height in inches. The second module accepts the student’s weight in pounds and converts the student’s height to centimeters and weight to grams. Then, it calculates the graduation gown size needed by adding 1/3 of the weight in grams to the value of the height in centimeters. The program’s output is the gown size the student should order. There are 2.54 centimeters in an inch and 453.59 grams in a pound. Use named constants wherever you think they are appropriate. The last module displays the message “End of job”.

Answer: A sample solution is as follows:

Hierarchy chart: main program housekeeping() detail() endOfJob() Flowchart:

Pseudocode:

start Declarations num studentInches num studentPounds num studentCm num studentGrams num studentSize num CENT_IN_INCH = 2.54 num GRAM_IN_POUND = 453.59 string HEIGHT_PROMPT = “Enter the student’s height in inches” string WEIGHT_PROMPT = “Enter the student’s weight in pounds” string END_LINE = “End of job” housekeeping() detail() endOfJob() stop housekeeping() output HEIGHT_PROMPT input studentInches return detail() output WEIGHT_PROMPT input studentPounds studentCm = studentInches * CENT_IN_INCH studentGrams = studentPounds * GRAM_IN_POUND studentSize = ((1 / 3) * studentGrams) + studentCm output studentSize return endOfJob() output END_LINE return b. Revise the size-determining program to execute continuously until the user enters 0 for the height in inches.

Answer: A sample solution is as follows:

b. Hierarchy chart: main program housekeeping() detailLoop() endOfJob() Flowchart:

Pseudocode:

start Declarations num studentFeet num studentInches num studentPounds num studentCm num studentGrams num studentSize num CENT_IN_INCH = 2.54 num GRAM_IN_POUND = 453.59 string HEIGHT_PROMPT = “Enter the student’s height in inches” string WEIGHT_PROMPT = “Enter the student’s weight in pounds” string END_LINE = “End of job” housekeeping() while not (studentInches = 0) detailLoop() endwhile endOfJob() stop housekeeping() output HEIGHT_PROMPT input studentInches return detailLoop() output WEIGHT_PROMPT input studentPounds studentCm = studentInches * CENT_IN_INCH studentGrams = studentPounds * GRAM_IN_POUND studentSize = ((1 / 3) * studentGrams) + studentCm output studentSize output HEIGHT_PROMPT input studentInches return endOfJob() output END_LINE return

7. Draw the hierarchy chart and design the logic for a program that contains housekeeping, detail loop, and end-of-job modules, and that calculates the service charge customers owe for writing a bad check. The main program declares any needed global variables and constants and calls the other modules. The housekeeping module displays a prompt for and accepts a customer’s last name. While the user does not enter “ZZZZ” for the name, the detail loop accepts the amount of the check in dollars and cents. The service charge is computed as $20 plus 2 percent of the check amount. The detail loop also displays the service charge and then prompts the user for the next customer’s name. The end-of-job module, which executes after the user enters the sentinel value for the name, displays a message that indicates the program is complete.

Answer: A sample solution is as follows:

Hierarchy chart: main program housekeeping() detailLoop() endOfJob() Flowchart:

Pseudocode:

start Declarations string customerLastName num checkAmount num serviceCharge num SERVICE_CHARGE_BASE = 20 num SERVICE_CHARGE_PERCT = 0.02 string NAME_PROMPT = “Enter the customer’s last name” string CHECK_PROMPT = “Enter the amount of the check in dollars and cents” string END_LINE = “Thank you for using the program” housekeeping() while not (customerLastName = “ZZZZ”) detailLoop() endwhile endOfJob() stop housekeeping() output NAME_PROMPT input customerLastName return detailLoop() output CHECK_PROMPT input checkAmount serviceCharge = SERVICE_CHARGE_BASE + SERVICE_CHARGE_PERCT * checkAmount output serviceCharge output NAME_PROMPT input customerLastName return endOfJob() output END_LINE return

8. Draw the hierarchy chart and design the logic for a program for the owner of Bits and Pieces Manufacturing Company, who needs to calculate an employee’s projected salary following a raise. The input is the name of the employee, the employee’s current weekly salary, and the percentage increase expressed as a decimal (for example, 0.04 for a 4 percent raise). Design the program so that it runs continuously for any number of employees using three modules. The housekeeping module prompts the user for the percent raise that will be applied to every employee, and prompts for the first employee’s name. The detail loop executes continuously until the user enters “XXX” for the employee’s name. The detail loop gets the employee’s weekly salary, applies the raise, produces the result, and prompts for the next employee name. The end-of-job module, which executes after the user enters the sentinel value for the name, displays a message that indicates the program is complete.

Answer: A sample solution is as follows:

Hierarchy chart: main program housekeeping() detailLoop() endOfJob() Flowchart:

Pseudocode:

start Declarations string employeeName num weeklySalary num percentIncrease num newSalary string NAME_PROMPT = “Enter the employee’s name” string PERCT_PROMPT = “Enter the percentage increase (as a decimal)” string SALARY_PROMPT = “Enter the weekly salary” string END_LINE = “Thank you for using the program” housekeeping() while not (employeeName = “XXX”) detailLoop() endwhile endOfJob() stop housekeeping() output PERCT_PROMPT input percentIncrease output NAME_PROMPT input employeeName return detailLoop() output SALARY_PROMPT input weeklySalary newSalary = weeklySalary * percentIncrease + weeklySalary output newSalary output NAME_PROMPT input employeeName return endOfJob() output END_LINE return

9. Draw the hierarchy chart and design the logic for a program for the manager of the Jeter County softball team, who wants to compute batting averages for his players. A batting average is computed as hits divided by at-bats, and is usually expressed to three decimal positions (for example, .235). Design a program that prompts the user for a player jersey number, the number of hits, and the number of at-bats, and then displays all the data, including the calculated batting average. The program accepts players continuously until 0 is entered for the jersey number. Use appropriate modules, including one that displays “End of job” after the sentinel is entered for the jersey number.

Answer: A sample solution is as follows:

Hierarchy chart: main program housekeeping() detailLoop() endOfJob() Flowchart:

Pseudocode:

start Declarations num jerseyNumber num numOfHits num numOfAtBats num battingAvg string NUM_PROMPT = “Enter the player’s jersey number” string HITS_PROMPT = “Enter the number of hits” string BATS_PROMPT = “Enter the number of at bats” string END_LINE = “End of job” housekeeping() while not (jerseyNumber = 0) detailLoop() endwhile endOfJob() stop housekeeping() output NUM_PROMPT input jerseyNumber return detailLoop() output HITS_PROMPT input numOfHits output BATS_PROMPT input numOfAtBats battingAvg = numOfHits / numOfAtBats output battingAvg output NUM_PROMPT input jerseyNumber return endOfJob() output END_LINE return