Answers to Selected Exercises

Transcription

1 DalePhatANS_complete 8/18/04 10:30 AM Page 1049 Answers to Selected Exercises Chapter 1 Exam Preparation Exercises 1. a. v, b. i, c. viii, d. iii, e. iv, f. vii, g. vi, h. ii. 2. Analysis and specification, general solution (algorithm), verify. 3. Concrete solution (program), test. 4. The analysis and specification step within the problem-solving phase. 5. The steps never end. Changing the last step to say, Repeat from first step until graduation, converts the sequence into an algorithm that eventually ends, assuming the person will graduate from school some day. We can make sure that this loop ends by specifying a condition that will definitely occur. For example, Repeat from first step until last day of classes. 6. a. vi, b. ii, c. v, d. i, e. vii, f. iv. 7. The program can be compiled on different computer systems without modification. 8. The control unit directs the actions of the other components in the computer to execute program instruction in the proper order. 9. False. The editor is software rather than hardware. 10. False. Peripheral devices are external to the CPU and its main memory. 11. Yes. If the software license restricts use to a single computer or a single user, then this is a case of piracy, even though you split the cost. 12. a. ii, b. v, c. iii, d. vii, e. i, f. vi, g. iv. Chapter 1 Programming Warm-Up Exercises 1. Branches: Steps n1, n2, and n3. There are two loops: steps p, q, and r; and steps t and u. Steps a, c, and e are references to subalgorithms defined elsewhere.

2 DalePhatANS_complete 8/18/04 10:30 AM Page Answers to Selected Exercises 2. follow separate algorithm for filling glass with water and placing on counter If right-handed, pick up toothpaste tube in left hand and unscrew cap by turning counter-clockwise place toothpaste cap on counter transfer toothpaste tube to right hand and pick up toothbrush in left hand, holding it by its handle place open end of toothpaste tube against tips of brush bristles and squeeze toothpaste tube just enough to create a 0.5-inch-long extrusion of toothpaste on brush pull toothpaste tube away from brush and place tube on counter transfer toothbrush to right hand, holding it by its handle open mouth and insert brush, placing toothpaste-covered bristles against one tooth scrub tooth with brush by moving brush up and down 10 times reposition brush to an unscrubbed tooth repeat previous two steps until all teeth have been brushed spit toothpaste into sink put toothbrush in sink pick up glass in right hand fill mouth with water from glass swish water in mouth for five seconds spit water from mouth into sink repeat previous three steps three times Otherwise (if left-handed) pick up toothpaste tube in right hand and unscrew cap by turning counter-clockwise place toothpaste cap on counter transfer toothpaste tube to left hand and pick up toothbrush in right hand, holding it by its handle place open end of toothpaste tube against tips of brush bristles and squeeze toothpaste tube just enough to create a 0.5-inch-long extrusion of toothpaste on brush pull toothpaste tube away from brush and place tube on counter transfer toothbrush to left hand, holding it by its handle open mouth and insert brush, placing toothpaste-covered bristles against one tooth scrub tooth with brush by moving brush up and down 10 times reposition brush to an unscrubbed tooth repeat previous two steps until all teeth have been brushed spit toothpaste into sink put toothbrush in sink pick up glass in left hand fill mouth with water from glass swish water in mouth for five seconds spit water from mouth into sink repeat previous three steps three times Place glass on counter Follow separate algorithm for cleaning up after brushing teeth

3 DalePhatANS_complete 8/18/04 10:30 AM Page 1051 Answers to Selected Exercises The test for right- or left-handedness is a branch. Each branch contains two loops, one that iterates until all teeth are brushed and another that iterates rinsing four times. The first and last steps refer to separately defined subalgorithms. 4. Change step u to: u. Repeat step t nine times. Chapter 1 Case Study Follow-Up Exercises 1. a No b Yes c Yes d No 2. a Line = 6 b Line = 2 c Line = 7 d Line = 4 e Line = 4 3. Divide by 1000 and see if the remainder is I was not, but your answer may be different. 5. Keep adding 1 to the year and test it until you find the next leap year. Another algorithm would be to use the following: nextyear = year + (year % 4) divide the nextyear by 100 and if the remainder isn t 0, Write that nextyear is the next leap year Otherwise, divide the nextyear by 400 and if the remainder isn t 0 Write that (nextyear + 4) is the next leap year Otherwise nextyear is the next leap year 6. Line Number 1 if (year % 4!= 0) 2 return false; 3 else if (year % 100!= 0) 4 return true; 5 else if (year % 400!= 0) 6 return false; 7 else return true; Chapter 2 Exam Preparation Exercises 1. a. valid, b. invalid (hyphens not allowed), c. invalid (reserved words not allowed), d. valid, e. valid, f. valid, g. invalid (must begin with a letter), h. invalid (# is not allowed). 2. a. vi, b. ix, c. iv, d. v, e. vii, f. ii, g. i, h. x, i. iii, j. viii. 3. False.

4 DalePhatANS_complete 8/18/04 10:30 AM Page Answers to Selected Exercises 4. The template allows an identifier to begin with a digit. Identifiers can begin with a letter or an underscore, and digits may appear only in the second character position and beyond. 5. False. 6. True. 7. True. 8. Note that the second line concatenates two words without a separating space. Four score and seven years agoour fathers brought forth on this continent a new nation Bjarne Stroustrup named his new programming language C++ because it is a successor to the C programming language. 10. By preceding it with a backslash character (\ ). 11. If we forget the */ at the end of a comment, then any number of lines of program code can be inadvertently included in the comment. The // form avoids this by automatically terminating at the end of the line. 12. The // form of comment cannot span more than one line. It also cannot be inserted into the middle of a line of code because everything to the right of // becomes a comment. 13. << is the stream insertion operator, and is pronounced put to or is sent, as in cout is sent string No. The endl identifier is a manipulator, and is not a string value. 15. It tells the C++ preprocessor to insert the contents of a specified file at that point in the code. 16. std::cout << "Hello everybody!" << std::endl; 17. A block. 18. By splitting it into pieces that fit on a line, and joining them with the concatenation operator. 19. #include <iostream> #include <string> using namespace std; const string TITLE = "Dr."; int main() cout << "Hello " + TITLE + " Stroustrup!"; Chapter 2 Programming Warm-Up Exercises 1. Substitute the actual data in the following: cout << "July 4, 2004" << endl;

5 DalePhatANS_complete 8/18/04 10:30 AM Page 1053 Answers to Selected Exercises Note that the \" escape sequence is needed in six places here: cout << "He said, \"How is that possible?\"" << endl << "She replied, \"Using manipulators.\"" << endl << "\"Of course,\" he exclaimed!" << endl; 3. a. const string ANSWER = "True"; b. char middleinitial; c. string coursetitle; d. const char PERCENT = '%' 4. const string FIRST = "Your first name inserted here"; const string LAST = "Your last name inserted here"; // Insert your middle initial in place of A: const char MIDDLE = 'A'; 5. cout << PART1 << PART2 << PART1 << PART3; 6. PART1 + PART2 + PART1 + PART3 7. cout << "Yet the web of thought has no such creases" << endl; cout << "And is more like a weaver's masterpieces;" << endl; cout << "One step a thousand threads arise," << endl; cout << "Hither and thither shoots each shuttle," << endl; cout << "The threads flow on unseen and subtle," << endl; cout << "Each blow effects a thousand ties." << endl; 8. #include <iostream> #include <string> using namespace std; const string TITLE = "Rev."; const char FIRST = 'H'; const char MID 'G'; const char DOT = '.'; int main() cout << TITLE << FIRST << DOT << MID << DOT << " Jones"; 9. The solution to this problem is for the student to show that he or she has run the program correctly. It should output: *********************************** * * * Welcome to C++ Programming! * * * ***********************************

6 DalePhatANS_complete 8/18/04 10:30 AM Page Answers to Selected Exercises Chapter 2 Case Study Follow-Up 1. const string BLACK = "%%%%%%%%"; // Define a line of a black square 2. const string WHITE = "..."; // Define a line of a white square 3. Move the first five output statements to the end of the program. 4. const string BLACK = "**********"; // Define a line of a black square const string WHITE = " "; // Define a line of a white square 5. // Chessboard program // This program prints a chessboard pattern that is built up from // basic strings of white and black characters. #include <iostream> #include <string> using namespace std; const string BLACK = "********"; // Define a line of a black square const string WHITE = " "; // Define a line of a white square const string BLACK_BLANK = "** **"; // Define a constant of embedded // blanks int main () string whiterow; // A row beginning with a white square string blackrow; // A row beginning with a black square string blackblankrow; // A black first row with mixed squares string whiteblankrow; // A white first row with mixed squares // Create a white-black row by concatenating the basic strings whiterow = WHITE + BLACK + WHITE + BLACK + WHITE + BLACK + WHITE + BLACK; // Create a white-black row with interior blanks in the blacks whiteblankrow = WHITE + BLACK_BLANK + WHITE + BLACK_BLANK + WHITE + BLACK_BLANK + WHITE + BLACK_BLANK; // Create a black-white row with interior blanks in the blacks blackblankrow = BLACK_BLANK + WHITE + BLACK_BLANK + WHITE + BLACK_BLANK + WHITE + BLACK_BLANK + WHITE;

7 DalePhatANS_complete 8/18/04 10:30 AM Page 1055 Answers to Selected Exercises 1055 // Create a black-white row by concatenating the basic strings blackrow = BLACK + WHITE + BLACK + WHITE + BLACK + WHITE + BLACK + WHITE; // Print five white-black rows cout << whiterow << endl; cout << whiterow << endl; cout << whiteblankrow << endl; cout << whiteblankrow << endl; cout << whiterow << endl; // Print five black-white rows cout << blackrow << endl; cout << blackrow << endl; cout << blackblankrow << endl; cout << blackblankrow << endl; cout << blackrow << endl; // Print five white-black rows cout << whiterow << endl; cout << whiterow << endl; cout << whiteblankrow << endl; cout << whiteblankrow << endl; cout << whiterow << endl; // Print five black-white rows cout << blackrow << endl; cout << blackrow << endl; cout << blackblankrow << endl; cout << blackblankrow << endl; cout << blackrow << endl; // Print five white-black rows cout << whiterow << endl; cout << whiterow << endl; cout << whiteblankrow << endl; cout << whiteblankrow << endl; cout << whiterow << endl;

8 DalePhatANS_complete 8/18/04 10:30 AM Page Answers to Selected Exercises // Print five black-white rows cout << blackrow << endl; cout << blackrow << endl; cout << blackblankrow << endl; cout << blackblankrow << endl; cout << blackrow << endl; // Print five white-black rows cout << whiterow << endl; cout << whiterow << endl; cout << whiteblankrow << endl; cout << whiteblankrow << endl; cout << whiterow << endl; // Print five black-white rows cout << blackrow << endl; cout << blackrow << endl; cout << blackblankrow << endl; cout << blackblankrow << endl; cout << blackrow << endl; return 0; 6. There are 64 characters per line, except for the results of Exercise 4, which would have 80 characters per line. Chapter 3 Exam Preparation Exercises 1. They are simple data types. 2. char, short, int, long. 3. Integer overflow. 4. E signifies an exponent in scientific notation. The digits to the left of the E are multiplied by 10 raised to the power given by the digits to the right of the E.

9 DalePhatANS_complete 8/18/04 10:30 AM Page 1057 Answers to Selected Exercises integer / constant / floating variable a. const int TRACKS_ON_DISK = 17; integer constant b. float timeoftrack; floating variable c. const float MAX_TIME_ON_DISK = 74.0; floating constant d. short tracksleft; integer variable e. float timeleft; floating variable f. long samplesintrack; integer variable g. const double SAMPLE_RATE = ; floating constant 6. Integer division with an integer result, and floating division with a floating result. 7. a. 21, b. 21.6, c. 13.0, d. 18, e. 20, f. 22, g () unary - [ * / % ] [ + - ] 9. True. 10. a. vi, b. ii, c. vii, d. iv, e. i, f. v, g. iii. 11. The ++ operator. 12. You write the name of a data type, followed by an expression enclosed in parentheses. 13. main returns an int value False. When used alone they are equivalent, but used within a larger expression, they can give different results (this is explained more in Chapter 10). 16. string::size_type 17. a. 29 b. 1 c. "ought to start with logic" d. 0 e. "log" f. 1 g. string::npos 18. It tells the stream to print floating-point numbers without using scientific notation. Chapter 3 Programming Warm-Up Exercises 1. (hours * 60 + minutes) * 60 + seconds 2. a. days / 7 b. days % 7 3. dollars * quarters * 25 + dimes *10 + nickels * 5 + pennies 4. float(dollars * quarters * 25 + dimes *10 + nickels * 5 + pennies) / count = count + 3; 6. a. 3 * X + Y b. A * A + 2 * B + C c. ((A + B)/(C D)) * (X / Y) d. ((A * A + 2 * B + C)/D) / (X * Y)

10 DalePhatANS_complete 8/18/04 10:30 AM Page Answers to Selected Exercises e. sqrt(fabs(a B)) f. pow(x, -cos(y)) 7. string temp; temp = sentence; first = temp.find("and"); // Get first location // Remove first section of string temp = temp.substr(first + 3, temp.length() (first + 3)); // Find second location of "and" in shortened string second = temp.find("and"); // Remove next section of string temp = temp.substr(second + 3, temp.length() (second + 3)); // Adjust second to account for deleting first part of string second = second + first + 3; // Locate third "and" and adjust for prior deletions third = temp.find("and") + second + 3; 8. startofmiddle = name.find(' ') + 1; 9. cout << "$" << fixed << setprecision(2) << setw(8) << money; 10. cout << setprecision(5) << setw(15) << distance; 11. #include <climits> cout << "INT_MAX = " << INT_MAX << " INT_MIN = " << INT_MIN; 12. //********************************************** // Celsius program // This program outputs the Celsius temperature // corresponding to a given Fahrenheit temperature //********************************************** #include <iostream> using namespace std; int main() const float FAHRENHEIT = 72.0;

11 DalePhatANS_complete 8/18/04 10:30 AM Page 1059 Answers to Selected Exercises 1059 float celsius; celsius = 5/9 * (FAHRENHEIT 32); cout << fixed << "Celsius equivalent of Fahrenheit " << FAHRENHEIT << " is " << celsius << " degrees."; return 0; Chapter 3 Case Study Follow-Up 1. cout << fixed << setprecision(2) << "For a loan amount of " << LOAN_AMOUNT << " with an interest rate of " << setprecision(4) << YEARLY_INTEREST << " and a " << NUMBER_OF_YEARS << " year mortgage, " << endl; cout << "your monthly payments are $" << setprecision(2) << payment << "." << endl; 2. Change the NUMBER_OF_YEARS to NUMBER_OF_MONTHS with the value 84. Remove numberofpayments and substitute NUMBER_OF_MONTHS where numberofpayments occurs. Change... const float LOAN_AMOUNT = ; // Amount of the loan const float YEARLY_INTEREST = ; // Yearly interest rate const int NUMBER_OF_MONTHS = 84; // Total number of payments int main() // local variables float monthlyinterest; // Monthly interest rate float payment; // Monthly payment // Calculate values monthlyinterest = YEARLY_INTEREST / 12; payment = (LOAN_AMOUNT * pow(monthlyinterest + 1, NUMBER_OF_MONTHS) * monthlyinterest)/(pow(monthlyinterest + 1, NUMBER_OF_MONTHS) - 1 ); // Output results cout << fixed << setprecision(2) << "For a loan amount of " << LOAN_AMOUNT << " with an interest rate of " << setprecision(4) << YEARLY_INTEREST << " and a "

12 DalePhatANS_complete 8/18/04 10:30 AM Page Answers to Selected Exercises << NUMBER_OF_MONTHS << " month mortgage, " << endl; cout << "your monthly payments are $" << setprecision(2) << payment << "." << endl; const float LOAN_AMOUNT = ; // Amount of the loan const float YEARLY_INTEREST = 5.24; // Yearly interest rate const int NUMBER_OF_MONTHS = 84; // Total number of payments int main() // local variables float monthlyinterest; // Monthly interest rate float payment; // Monthly payment // Calculate values monthlyinterest = YEARLY_INTEREST * 0.01 / 12; payment = (LOAN_AMOUNT * pow(monthlyinterest + 1, NUMBER_OF_MONTHS) * monthlyinterest)/(pow(monthlyinterest + 1, NUMBER_OF_MONTHS) - 1 ); // Output results cout << fixed << setprecision(2) << "For a loan amount of " << LOAN_AMOUNT << " with an interest rate of " << YEARLY_INTEREST << " and a " << NUMBER_OF_MONTHS << " month mortgage, " << endl; cout << "your monthly payments are $" << payment << "." << endl; float oneplus; // Monthly interest plus 1 // Calculate values monthlyinterest = YEARLY_INTEREST * 0.01 / 12; oneplus = monthlyinterest + 1; payment = (LOAN_AMOUNT * pow(oneplus, NUMBER_OF_MONTHS) * monthlyinterest/(pow(oneplus, NUMBER_OF_MONTHS) - 1;...

13 DalePhatANS_complete 8/18/04 10:30 AM Page 1061 Answers to Selected Exercises 1061 If an expression is duplicated more than twice, it probably should be calculated and saved. If an expression is used only twice but is a complex expression, it probably should be calculated and saved. The duplicate expression in this program is simple and is used only twice; it probably isn t worth the extra storage. Chapter 4 Exam Preparation Exercises 1. False. The two statements input the values in reverse order with respect to the single statement s inputs. 2. a. The insertion operator cannot be used with cin. b. The extraction operator cannot be used with cout. c. The right operand of the extraction operator must be a variable. d. The arguments are in reverse order. e. The function name should not have a capital L, and the arguments are reversed. 3. a = 70, b = 80, c = 30, d = 40, e = 50, f = a = 70, b = 80, c = 30, d = 0, e = 20, f = a. string1 = "January", string2 = "25," b. The reading marker is on the space following the comma. 6. a. string1 = "January 25, 2005" b. The reading marker is at the start of the next line. 7. a. string1 = "January", int1 = 25, char1 = ',', string2 = "2005" b. The reading marker is on the newline character at the end of the line. 8. It returns \n. 9. The first argument is a maximum number of characters to skip over. The second argument specifies a character that the function searches for. If it finds the character before skipping the maximum number of characters, then it stops with the reading marker on the following character. 10. Some variation in the answer is acceptable, as long as it is clear that the prompt for the inexperienced user is much more detailed. a. cout << "Enter a date in the format of mm/dd/yyyy." << " For example, for October 18, 1989, enter 10/18/1989."; b. cout << "Enter date, format mm/dd/yyyy."; 11. Include the header file fstream. Declare the file stream. Prepare the file with open. Specify the name of the file stream in each I/O statement. 12. ifstream and ofstream. 13. The first statement declares infile to be an input file stream. The second statement opens infile, associating it with a file called datafile.dat by the operating system. 14. The correction is to convert the name into a C string. ifstream indata; string name; cout << "Enter the name of the file: "); cin >> name; infile.open(name.c_str());

14 DalePhatANS_complete 8/18/04 10:30 AM Page Answers to Selected Exercises 15. The input operation is ignored. 16. False. The file immediately enters the fail state, and I/O operations on it are simply ignored. 17. False. If the file doesn t exist, it can open in the fail state. 18. The answer can vary, but should at least include vehicle, customer, and agency. A little more thought might add garage, repair shop, contract, and so on. 19. The class. 20. a. A step for which the implementation details are fully specified. b. A step for which some implementation details remain to be specified. c. A self-contained series of steps that solves a given problem or subproblem. d. A module that performs the same operation as the abstract step it defines. e. A property of a module in which the concrete steps are all directed to solving just one problem, and any significant subproblems are written as abstract steps. 21. The function. 22. a. no, b. yes, c. yes, d. no, e. no. 23. True. Chapter 4 Programming Warm-Up Exercises 1. cin >> int1 >> int2 >> int3; 2. cout << "Enter a name in the format: first middle last:"; cin >> first >> middle >> last; 3. cout << "Enter a name in the format: first middle last:"; getline(cin, name); 4. float number1; float number2; float number3; float average; cout << "Enter the first number and press return: "; cin >> number1; cout << "Enter the second number and press return: "; cin >> number2; cout << "Enter the third number and press return: "; cin >> number3; average = (number1 + number2 + number3) / 3.0; cout << "The average is: " << average << endl; 5. float number1; float number2; float number3; float average; cout << "Enter the three numbers separated by spaces: "; cin >> number1 >> number2 >> number3;

15 DalePhatANS_complete 8/18/04 10:30 AM Page 1063 Answers to Selected Exercises 1063 average = (number1 + number2 + number3) / 3.0; cout << "The average is: " << average << endl; 6. The names of the variables may differ from those shown here. Instead of using the ignore function to skip a single character, reading into a dummy char variable may also be used. a. int int1; char char1; float float1; cin >> int1 >> char1 >> float1; b. string string1; string string2; int int1; int int2; cin >> string1 >> int1 >> string2 >> int2; c. int int1; int int2; float float1; cin >> int1; cin.ignore(1, ','); cin >> int2; cin.ignore(1, ','); cin >> float1; d. char char1; char char2; char char3; char char4; cin >> char1; cin.ignore(1, ' '); cin >> char2; cin.ignore(1, ' '); cin >> char3; cin.ignore(1, ' '); cin >> char4; cin.ignore(1, ' '); e. float float1; cin.ignore(1, '$'); cin >> float1;

16 DalePhatANS_complete 8/18/04 10:30 AM Page Answers to Selected Exercises 7. In this solution the comma is included as part of the city name. cin >> streetnum >> street1 >> street2 >> town >> state >> zip; 8. #include <fstream> fstream temps; temps.open("temperatures.dat"); 9. An alternative approach is to declare one temp variable that is reused for each of six input statements, and keep a running total of the input values. float temp1; float temp2; float temp3; float temp4; float temp5; float temp6; float average; temps >> temp1 >> temp2 >> temp3 >> temp4 >> temp15 >> temp6; average = (temp1 + temp2 + temp3 + temp4 + temp5 + temp6) / 6.0; cout << "The average temperature is: " << average; 10. #include <iostream> #include <fstream> using namespace std; fstream indata; fstream outdata; const float PI = ; float radius; float circumference; float area; int main() indata.open("indata.dat"); outdata.open("outdata.dat"); indata >> radius; circumference = radius * 2 * PI; area = radius * radius * PI; cout << "For the first circle, the circumference is " << circumference << " and the area is " << area << endl; outdata << radius << " " << circumference << " " << area << endl; indata >> radius;

17 DalePhatANS_complete 8/18/04 10:30 AM Page 1065 Answers to Selected Exercises 1065 circumference = radius * 2 * PI; area = radius * radius * PI; cout << "For the second circle, the circumference is " << circumference << " and the area is " << area << endl; outdata << radius << " " << circumference << " " << area << endl; 11. Changed lines are underlined. #include <iostream> #include <fstream> using namespace std; fstream indata; fstream outdata; const float PI = ; float radius; float circumference; float area; string filename; int main() indata.open("indata.dat"); cout << "Enter the name of the file to open: "; cin >> filename; outdata.open(filename.c_str()); // The remainder of the program is unchanged 12. infile >> int1 >> int2 >> int3; 13. cout << "Enter the name of the file to open: "; cin >> filename; userfile.open(filename.c_str()); 14. Top level: Write letter Mail letter

18 DalePhatANS_complete 8/18/04 10:30 AM Page Answers to Selected Exercises Level 2 Write letter Write return address and date Write company address Write salutation Write body of letter Write closing Sign letter Mail letter Address envelope Write return address Attach stamp to envelope Fold letter in thirds Insert letter in envelope Seal envelope Place envelope in mail box 15. Letter and envelope are the main objects. Other objects include: return address, company address, salutation, letter body, closing, signature, stamp, and mail box. Chapter 4 Case Study Follow-Up 1. The answer will vary with each student. 2. // Output information in required formats outdata << socialnum << endl; outdata << " " << firstname << ' ' << middlename << ' ' << lastname << ' ' << endl; outdata << " " << lastname << ", " << firstname << ' ' << middlename << ' ' << endl; outdata << " " << lastname << ", " << firstname << ' ' << initial << ' ' << endl; outdata << " " << firstname << ' ' << initial << ' ' << lastname; 3. #include <iostream> // Access cin and cout #include <fstream> // Access open... // Declare and open files ifstream indata; ofstream outdata; string filename; cout << "Enter the name of the input file: ";

19 DalePhatANS_complete 8/18/04 10:30 AM Page 1067 Answers to Selected Exercises cin >> filename; indata.open(filename.c_str()); outdata.open("name.out"); 4. #include <iostream> // Access cin and cout #include <fstream> // Access open... // Declare and open files ifstream indata; ofstream outdata; string filename; cout << "Enter the name of the input file: "; cin >> filename; indata.open(filename.c_str()); cout << "Enter the name of the output file: "; cin >> filename; outdata.open(filename.c_str()); // Mortgage Payment Calculator program // This program determines the monthly payments on a mortgage given // the loan amount, the yearly interest, and the number of years. #include <iostream> #include <cmath> #include <iomanip> using namespace std; int main() // Input variables float loanamount; float yearlyinterest; int numberofyears; // local variables float monthlyinterest; int numberofpayments; float payment;

20 DalePhatANS_complete 8/18/04 10:30 AM Page Answers to Selected Exercises // Prompt for and read input values cout << "Input the total loan amount (ex: )" << endl; cin >> loanamount; cout << "Input the interest rate (ex: 6.25)" << endl; cin >> yearlyinterest; cout << "Enter the number of years for the loan (ex: 15)" << endl; cin >> numberofyears; // Calculate values monthlyinterest = yearlyinterest * 0.01/ 12.0; numberofpayments = numberofyears * 12; payment = (loanamount * pow(1 + monthlyinterest, numberofpayments) * monthlyinterest)/ ( pow(1 + monthlyinterest, numberofpayments) - 1 ); // Output results cout << fixed << setprecision(2) << "For a loan amount of " << loanamount << " with an interest rate of " << yearlyinterest << " and a " << numberofyears << " year mortgage, " << endl; cout << fixed << setprecision(2) << "your monthly payments are $" << payment << "." << endl; return 0; Chapter 5 Exam Preparation Exercises 1. The order in which the computer executes statements in a program. 2. False. They are predefined constants. 3. False. It is >=. 4. Because, in the collating sequence of the character set, the uppercase letters all come before the lowercase letters. 5. a. true b. true c. true d. false e. false

21 DalePhatANS_complete 8/18/04 10:31 AM Page 1069 Answers to Selected Exercises 1069 f. true g. true 6. a. true b. true c. true d. true e. true f. false g. false 7. Because conditional or short-circuit evaluation prevents the second part of the expression from being evaluated when someint is True. 9. False. The parentheses are required. 10. It outputs The data doesn't make sense." 11. It outputs The word may be "The" 12. Nothing. 13. Because the test is written with = instead of ==, so the expression is always false. 14. It outputs Very good 15. Very goodexcellent 16. Add braces to enclose the If-Then statement. 17.!inData 18. There is no limit, although a human reader finds it difficult to follow too many levels. Chapter 5 Programming Warm-Up Exercises 1. moon == "blue" moon == "Blue" 2.!inFile1 &&!infile2 3. if (infile) cin >> somestring; 4. if (year1 < year2 && month1 < month2 && day1 < day2) cout << month1 << "/" << day1 << "/" year1 << " comes before " << month2 << "/' << day2 << "/" << year2; else cout << month1 << "/" << day1 << "/" year1 << " does not come before " << month2 << "/' << day2 << "/" << year2; 5. if (year1 < year2 && month1 < month2 && day1 < day2) cout << month1 << "/" << day1 << "/" year 1 << " comes before " << month2 << "/' << day2 << "/" << year2; else cout << month1 << "/" << day1 << "/" year1 << " does not come before "

22 DalePhatANS_complete 8/18/04 10:31 AM Page Answers to Selected Exercises << month2 << "/' << day2 << "/" << year2; month1 = month2; day1 = day2; year1 = year2; 6. bool1 bool2 &&!(bool1 && bool2) 7. if (score < 0 score > 100) cout << "Score is out of range"; 8. if (score < 0 score > 100) cout << "Score is out of range"; else scoretotal = scoretotal + score; scorecount++; 9. infile1 >> value1; infile2 >> value2; if (!infile1 &&!infile2) cout << "File error."; else if (!infile1!infile2) if (infile1) outfile << value1; else outfile << value2; else if (value1 < value2); outfile << value1; infile1 >> value1; else outfile << value2; infile2 >> value2; 10. if (score > 100) cout << "Duffer."; else if (score > 80) cout << "Weekend regular."; else if (score > 72) cout << "Competitive player."; else if (score > 68) cout << "Turn pro!"; else

23 DalePhatANS_complete 8/18/04 10:31 AM Page 1071 Answers to Selected Exercises 1071 cout << "Time to go on tour!"; 11. if (count1 <= count2 && count1 <= count3) cout << count1; if (count1 == count2) cout << count2; if (count1 == count3) cout << count3; else if (count2 <= count3) cout << count2; if (count2 == count3) cout << count3; else cout << count3; 12. The conditional tests are using = instead of ==. Both branches have the error, but the second one doesn t output the message because the result of the assignment expression is 0, which is treated as false by the branch. maximum = 75; minimum = 25; if (maximum == 100) cout << "Error in maximum: " << maximum << endl; if (minimum == 0) cout << "Error in minimum: " << minimum << endl; 13. if (area < 0) area = -area; root = sqrt(area); else root = sqrt(area); 14. Values of temp that should be tried are: 213, 212, 211, 33, 32, Combinations of values for month, day, and year that should be tested are as follows: Month Day Year Tests first condition of first branch not taken Tests second condition of first branch not taken Tests first branch taken, second branch taken Tests first branch taken, second not taken Tests first branch taken, second not taken, third taken

24 DalePhatANS_complete 8/18/04 10:31 AM Page Answers to Selected Exercises Chapter 5 Case Study Follow-Up 1. You could plug the BMI cut-off value and a value for weight into the formula and solve it for the height; however, the body mass index is calculated using real arithmetic. The number of decimal places must be very accurate to get the exact BMI value for which you are looking. A better choice is to round the BMI value so that you are testing two integers. 2. There is no unique answer, but the following values will work. 120, , , , // BMI Program // This program calculates the body mass index (BMI) given a weight // in pounds and a height in inches and prints a health message // based on the BMI. Input in metric measures. #include <iostream> using namespace std; int main() float weight; // Weight in kilograms float height; // Height in meters float bodymassindex; // Appropriate BMI bool dataareok; // True if data non-negative // Prompt for and input weight and height cout << "Enter your weight in kilograms. " << endl; cin >> weight; cout << "Enter your height in meters. " << endl; cin >> height; // Test Data if (weight < 0 height < 0) dataareok = false; else dataareok = true;

25 DalePhatANS_complete 8/18/04 10:31 AM Page 1073 Answers to Selected Exercises 1073 if (dataareok) // Calculate body mass index bodymassindex = weight / (height * height); // Print message indicating status cout << "Your body mass index is " << bodymassindex << ". " << endl; cout << "Interpretation and instructions. " << endl; if (bodymassindex < 18.5) cout << "Underweight: Have a milkshake." << endl; else if (bodymassindex < 25.0) cout << "Normal: Have a glass of milk." << endl; else if (bodymassindex < 30.0) cout << "Overweight: Have a glass of iced tea." << endl; else cout << "Obese: See your doctor." << endl; else cout << "Invalid data; weight and height must be positive." << endl; return 0; 4. // BMI Program // This program calculates the body mass index (BMI) given a weight // in pounds and a height in feet and inches and prints a health // based message on the BMI. Input in English measures. #include <iostream> using namespace std; int main() const int BMI_CONSTANT = 703; float weight; float inches; float feet; float height; float bodymassindex; bool dataareok; // Constant in nonmetric formula // Weight in pounds // Remainder of height in inches // Height in feet // Complete height in inches // Appropriate BMI // True if data non-negative

26 DalePhatANS_complete 8/18/04 10:31 AM Page Answers to Selected Exercises // Prompt for and input weight and height cout << "Enter your weight in pounds: " ; cin >> weight; cout << "Enter your height in feet and inches. " << endl; cout << "Feet: " ; cin >> feet; cout << "Inches: " ; cin >> inches; height = feet * 12 + inches; // Test Data if (weight < 0 height < 0) dataareok = false; else dataareok = true; if (dataareok) // Calculate body mass index bodymassindex = weight * BMI_CONSTANT / (height * height); // Print message indicating status cout << "Your body mass index is " << bodymassindex << ". " << endl; cout << "Interpretation and instructions. " << endl; if (bodymassindex < 18.5) cout << "Underweight: Have a milkshake." << endl; else if (bodymassindex < 25.0) cout << "Normal: Have a glass of milk." << endl; else if (bodymassindex < 30.0) cout << "Overweight: Have a glass of iced tea." << endl; else cout << "Obese: See your doctor." << endl; else cout << "Invalid data; weight and height " << "must be positive." << endl; return 0;

27 DalePhatANS_complete 8/18/04 10:31 AM Page 1075 Answers to Selected Exercises The weight and height are checked to be sure they are not negative before the BMI is calculated in this program. There are several other things that could be done. For example, if the weight is less than the height, then there is an error. In fact, if the weight is less than one and a half times the height, there is a good chance that there is an error. This condition produces very low BMIs. What about weights that are six or seven times the height? These produce very high BMIs. Another approach would be to put a check on the BMI itself. If it is below 10 or greater than 60, there is a good chance of input errors. Chapter 6 Exam Preparation Exercises 1. False. 2. False. 3. True. 4. a. ii, b. ix, c. iv, d. viii, e. vi, f. i, g. v, h. vii, i. iii. 5. Twelve times Twelve times. 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 7. Twelve times. $1.00 $2.00 $3.00 $4.00 $5.00 $6.00 $7.00 $8.00 $9.00 $10.00 $11.00 $12.00

28 DalePhatANS_complete 8/18/04 10:31 AM Page Answers to Selected Exercises 8. The @@@@@@@@@@@ 9. The output is: The code fails to process the first value on the file. The corrected code is: sum = 0; indata >> number; while (indata) sum = sum + number; indata >> number; 11. You could choose anything that s not a name. A blank line would be one possibility. If the program must read the name in three parts, then a series of nonalphabetic characters, separated appropriately, would work. For example: The output is: The corrected code is: number = 0; while (number < 10)

29 DalePhatANS_complete 8/18/04 10:31 AM Page 1077 Answers to Selected Exercises 1077 cout << number * 2 1 << " "; number++; 13. False. 14. What is the condition that ends the loop? How should the condition be initialized? How should the condition be updated? What is the process being repeated? How should the process be initialized? How should the process by updated? What is the state of the program on exiting the loop? 15. The sum is not reinitialized at the start of each inner loop, so it simply keeps accumulating the input values. The count isn t updated, so the flow of control doesn t leave the inner loop until the end-of-file condition is encountered. Here is the corrected code. while (indata) count = 1; sum = 0; while (count <= 5 && indata) cin >> number; sum = sum + number; count++; cout << sum / count << endl; Chapter 6 Programming Warm-Up Exercises 1. count = -10; while (count <= 10) cout << count << endl; count++; 2. count = 1; sum = 0; while (sum <= 10000) sum = sum + count; count++; cout << count 1;

30 DalePhatANS_complete 8/18/04 10:31 AM Page Answers to Selected Exercises 3. count = 0; sum = 0; indata >> score; while (indata && count < 20) sum = sum + score; count++; indata >> score; if (count == 0) cout << "No data on file."; else cout << "Average is " << sum / count << endl; 4. count = 0; getline(chapter6, line); while (chapter6) if (line.find("code segment") < string::npos) count++; getline(chapter6, line); cout << "The string was found " << count << " times." 5. cin >> response; while (!(response == "Yes" response == "yes" response == "No" response == "no")) cout << "Invalid response. Please enter \"Yes\" or \"No\"."; cin >> response; yes = response == "Yes" response == "yes"; 6. cout << "Sun Mon Tue Wed Thu Fri Sat" << endl; count = 1; while (count <= startday) //Print blanks in first week cout << " "; count++; daynumber = 1; while (daynumber <= days) //Print day numbers for month while (count <= 7) //Print for one week in month if (daynumber <= days)

31 DalePhatANS_complete 8/18/04 10:31 AM Page 1079 Answers to Selected Exercises 1079 cout << setw(3) << daynumber << " "; count++; daynumber++; cout << endl; count = 1; 7. a. startday = (startday + days) % 7; b. We would need the number of days in each successive month. 8. char onechar; int ecount; int charcount; ecount = 0; textdata >> onechar; charcount = 0; while (textdata) charcount++; if (onechar == 'z') ecount++; textdata >> onechar; cout << "Percentage of letter 'z': " << float(ecount) / charcount * 100; 9. char onechar; int ecount; int charcount; ecount = 0; textdata >> onechar; charcount = 0; while (textdata && charcount < 10000) charcount++; if (onechar == 'z') ecount++; textdata >> onechar; cout << "Percentage of letter 'z': " << float(ecount) / charcount * 100; 10. first = 1; second = 1; cout << first << endl << second << endl; while (second < 30000)

32 DalePhatANS_complete 8/18/04 10:31 AM Page Answers to Selected Exercises next = first + second; first = second; second = next; cout << second << endl; 11. first = 1; second = 1; cout << setw(5) << 1 << setw(8) << first << endl << setw(5) << 1 << setw(8) << second << endl; position = 2; while (second < 30000) next = first + second; first = second; second = next; position++; cout << setw(5) << position << setw(8) << second << endl; 12. cout << "Enter number of stars: "; cin >> number; count = 1; while (count <= number) cout << '*'; count++; ) cout << endl; 13. The loop ends when the specified number of stars has been printed. The condition is initialized by getting the number of stars, and setting the loop iteration counter to 1. The condition is updated by incrementing the iteration counter at the end of each iteration. The process being repeated is the printing of a single star. The process does not require any initialization or update. Upon exiting the loop, the specified number of stars has been printed, and the iteration counter is equal to the number plus one. 14. indata >> number; while (indata) count = 1; while (count <= number) cout << '*'; count++;

33 DalePhatANS_complete 8/18/04 10:31 AM Page 1081 Answers to Selected Exercises 1081 cout << endl; indata >> number; 15. The code should be tested with an empty file, a file that contains one value, and a file that contains multiple values. The values should include a negative integer, zero, and positive integers. Chapter 6 Case Study Follow-Up 1. if (current >= high) // Check for new high 2. if (preceding <= low) 3. Yes; a priming read is used because the first value read is special and needs to be processed outside the loop. Normally, a priming read is not used with a count-controlled loop. 4. Count-controlled. 5. Changing the input to come from the keyboard is easy: cout replaces all references to the file name in output statements and all other references to the file are removed. However, because the output is also going to the screen, it will be intermingled with the prompts and the input. If you are careful, you can make the screen readable, but if the input is from the keyboard, it is better for the output to go to a file. 6. Often the amount of data determines whether it should be entered into a file rather than entered at the keyboard. Another factor is where the data is coming from. In this case, values are being recorded by a machine, so it is logical to have them go directly to a file. 7. We should try data sets that present the highest value and lowest dip in different places and in different orders. For example, we should try one set with the highest reading as the first value and another set with it as the last. We should try test data with no dips (all the readings equal), with multiple dips, and with the lowest dip before, after, and between other dips. Finally, we should try the program on some typical sets of readings and check the output with results we ve determined by hand. Chapter 7 Exam Preparation Exercises 1. It uses the keyword void instead of int, the function is not called main, and it does not contain a return statement. 2. False. The parameter name is optional. 3. Control returns after the last statement has executed, and returns to the statement immediately following the call. 4. a. v, b. iii, c. vi, d. i, e. iv, f. viii, g. ii, h. vii. 5. name and salary are reference parameters. age and level are value parameters. 6. The call must have six arguments, unless default parameters are used (we do not cover their use in this book, but they are mentioned). 7. The value parameter stores the new value but the argument is unaffected. The reference parameter stores the new value directly into the argument. 8. The type must come before the name of each parameter instead of after it. The & should be appended to the type instead of to the parameter name. The prototype should end with a semicolon.

34 DalePhatANS_complete 8/18/04 10:31 AM Page Answers to Selected Exercises 9. False. Arguments must appear in the same order as the corresponding parameters. 10. Hiding a module implementation in a separate block with a formally specified interface. 11. Flow out, or in and out. 12. It should not contain a return statement. 13. The result is not passed back to the caller it should be a reference parameter instead of a local variable. 14. The result is not passed back to the caller result should be a reference parameter instead of a value parameter. 15. The x and y parameters should be value parameters their data flow is inward only. In the case of the y parameter, the value of the argument will be set to zero when the function returns. 16. False. Like any other variable declaration, it can be accessed only by statements within the block that follows its declaration. 17. True. 18. That the file contains valid data (only integers), and that it has at least one value (the mean is undefined for an empty data set). Chapter 7 Programming Warm-Up Exercises 1. void Max (/* in */ int num1, /* in */ int num2, /* out */ int& greatest) 2. void Max (int, int, int&); 3. void Max (/* in */ int num1, /* in */ int num2, /* out */ int& greatest) if (num1 > num2) greatest = num1; else greatest = num2; 4. void GetLeast (/* inout */ ifstream& infile, /* out */ int& lowest) 5. void GetLeast (ifstream&, int&); 6. void GetLeast (/* inout */ ifstream& infile, /* out */ int& lowest) int number; infile >> number; // Get a number lowest = INT_MAX; // Initially use greatest int while (infile) if (number < lowest)

35 DalePhatANS_complete 8/18/04 10:31 AM Page 1083 Answers to Selected Exercises 1083 lowest = number; infile >> number; // Remember lower number // Get next number 7. // Precondition: // File infile has been opened AND // header file climits has been included // File infile is at end-of-file AND // if the file is empty, lowest contains INT_MAX; // else smallest number on file infile is in lowest 8. void Reverse ( /* in */ string original, /* out */ string& lanigiro ) 9. void Reverse ( string, string& ); 10. void Reverse ( /* in */ string original, /* out */ string& lanigiro ) int count; count = 1; lanigiro = ""; while (count <= original.length()) lanigiro = lanigiro + original.substr(original.length() - count, 1); count++; ) 11. // Precondition: // Original must have a value // lanigiro contains the reverse of the string in original 12. void LowerCount ( /* out */ int& count) char inchar; count = 0; cin >> inchar; while (cin && inchar!= '\n') if (islower(inchar)) count++; cin >> inchar;

36 DalePhatANS_complete 8/18/04 10:31 AM Page Answers to Selected Exercises 13. // Precondition: // The program has included the header cctype // A line has been read from cin AND // the number of lowercase letters on the line is in count 14. void GetNonemptyLine ( /* inout */ ifstream& infile, /* out */ string& line) getline(infile, line); while (infile && line == "") getline(infile, line); 15. void SkipToEmptyLine ( /* inout */ ifstream& infile, /* out */ int& skipped) skipped = 0; getline(infile, line); while (infile && line!= "") skipped++; getline(infile, line); 16. void TimeAdd ( /* inout */ int& days, /* inout */ int& hours, /* inout */ int& minutes, /* in */ int adddays, /* in */ int addhours, /* in */ int addminutes) int extrahour; int extraday; minutes = (minutes + addminutes) % 60; extrahour = (minutes + addminutes) / 60; hours = (hours + addhours + extrahour) % 24; extraday = (hours + addhours + extrahour) / 24; days = days + adddays + extraday; 17. void TimeAdd ( /* inout */ int& days, /* inout */ int& hours, /* inout */ int& minutes, /* inout */ int& seconds,

37 DalePhatANS_complete 8/18/04 10:31 AM Page 1085 Answers to Selected Exercises 1085 /* in */ int adddays, /* in */ int addhours, /* in */ int addminutes, /* in */ int addseconds) int extraminute; int extrahour; int extraday; seconds = (seconds + addseconds) % 60; extraminute = (seconds + addseconds) / 60; minutes = (minutes + addminutes + extraminute) % 60; extrahour = (minutes + addminutes + extraminute) / 60; hours = (hours + addhours + extrahour) % 24; extraday = (hours + addhours + extrahour) / 24; days = days + adddays + extraday; 18. void SeasonPrint (/* in */ int month, /* in */ int day); if (month == 12 && day >= 21) cout << "Winter"; else if ((month == 9 and day >= 21) month > 9) cout << "Fall"; else if ((month == 6 and day >= 21) month > 6) cout << "Summer"; else if ((month == 3 and day >= 21) month > 3) cout << "Spring"; else cout << "Winter"; Chapter 7 Case Study Follow-Up Exercises 1. //***************************************************************** // Mortgage Payment Tables program // This program prints a table showing loan amount, interest rate, // length of loan, monthly payments, and total cost of a mortgage. #include <iostream> #include <cmath> #include <iomanip> #include <fstream> using namespace std;

38 DalePhatANS_complete 8/18/04 10:31 AM Page Answers to Selected Exercises // Function prototypes void PrintHeading(ofstream&); void GetLoanAmount(float&); void GetRestOfData(float&, int&); void DeterminePayment(float, int, float, float&); void PrintResults(ofstream&, float, int, float, float); int main() // Input variables float loanamount; float yearlyrate; int numberofyears; float payment; ofstream dataout; dataout.open("mortgage.out"); PrintHeading(dataOut); // Prompt for and read input values GetLoanAmount(loanAmount); while (loanamount > 0.0) GetRestOfData(yearlyRate, numberofyears); DeterminePayment(loanAmount, numberofyears, yearlyrate, payment); PrintResults(dataOut, loanamount, numberofyears, yearlyrate, payment); GetLoanAmount(loanAmount); dataout.close(); return 0; void PrintHeading(ofstream& dataout) dataout << fixed << setprecision(2) << setw(12) << "Loan Amount" << setw(12) << "No. Years" << setw(15) << "Interest Rate" << setw(12) << "Payment" << setw(12) << "Total Paid" << endl;