Solutions for H7. Lecture: Xu Ying Liu

Transcription

1 Lecture: Xu Ying Liu Ex // Exercise Solution: Date.h 2 // Date class definition. 3 #ifndef DATE_H 4 #define DATE_H 6 #include <iostream> 7 using namespace std; 8 9 class Date 10 { 11 friend ostream &operator<<( ostream &, const Date & ); 12 public: 13 Date( int m = 1, int d = 1, int y = 1900 ); // default constructor 14 void setdate( int, int, int ); // set month, day, year 1 Date &operator++(); // prefix increment operator 16 Date operator++( int ); // postfix increment operator 17 const Date &operator+=( int ); // add days, modify object 18 bool leapyear( int ) const; // is date in a leap year? 19 bool endofmonth( int ) const; // is date at the end of month? 20 int getmonth() const; // return the month of the date 21 private: 22 int month; 23 int day; 24 int year; 2 26 static const int days[]; // array of days per month 27 void helpincrement(); // utility function for incrementing date 28 }; // end class Date #endif 1 // Exercise Solution: Date.cpp 2 // Date class member-function definitions. 3 #include <iostream> 4 #include "Date.h"

2 6 // initialize static member at file scope; one classwide copy 7 const int Date::days[] = 8 { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; 9 10 // Date constructor 11 Date::Date( int m, int d, int y ) 12 { 13 setdate( m, d, y ); 14 } // end Date constructor 1 16 // set month, day and year 17 void Date::setDate( int mm, int dd, int yy ) 18 { 19 month = ( mm >= 1 && mm <= 12 )? mm : 1; 20 year = ( yy >= 1900 && yy <= 2100 )? yy : 1900; // test for a leap year 23 if ( month == 2 && leapyear( year ) ) 24 day = ( dd >= 1 && dd <= 29 )? dd : 1; 2 else 26 day = ( dd >= 1 && dd <= days[ month ] )? dd : 1; 27 } // end function setdate // overloaded prefix increment operator 30 Date &Date::operator++() 31 { 32 helpincrement(); // increment date 33 return *this; // reference return to create an lvalue 34 } // end function operator // overloaded postfix increment operator; note that the 37 // dummy integer parameter does not have a parameter name 38 Date Date::operator++( int ) 39 { 40 Date temp = *this; // hold current state of object 41 helpincrement(); // return unincremented, saved, temporary object 44 return temp; // value return; not a reference return 4 } // end function operator // add specified number of days to date 48 const Date &Date::operator+=( int additionaldays ) 49 { 0 for ( int i = 0; i < additionaldays; i++ ) 2

3 1 helpincrement(); 2 3 return *this; // enables cascading 4 } // end function operator+= 6 // if the year is a leap year, return true; otherwise, return false 7 bool Date::leapYear( int testyear ) const 8 { 9 if ( testyear % 400 == 0 60 ( testyear % 100!= 0 && testyear % 4 == 0 ) ) 61 return true; // a leap year 62 else 63 return false; // not a leap year 64 } // end function leapyear 6 66 // return the month of the date 67 int Date::getMonth() const 68 { 69 return month; 70 } // end function getmonth // determine whether the day is the last day of the month 73 bool Date::endOfMonth( int testday ) const 74 { 7 if ( month == 2 && leapyear( year ) ) 76 return testday == 29; // last day of Feb. in leap year 77 else 78 return testday == days[ month ]; 79 } // end function endofmonth // function to help increment the date 82 void Date::helpIncrement() 83 { 84 // day is not end of month 8 if (!endofmonth( day ) ) 86 day++; // increment day 87 else 88 if ( month < 12 ) // day is end of month and month < { 90 month++; // increment month 91 day = 1; // first day of new month 92 } // end if 93 else // last day of year 94 { 9 year++; // increment year 96 month = 1; // first month of new year 3

4 97 day = 1; // first day of new month 98 } // end else 99 } // end function helpincrement // overloaded output operator 102 ostream &operator<<( ostream &output, const Date &d ) 103 { 104 static char *monthname[ 13 ] = { "", "January", "February", 10 "March", "April", "May", "June", "July", "August", 106 "September", "October", "November", "December" }; 107 output << monthname[ d.month ] << ' ' << d.day << ", " << d.year; 108 return output; // enables cascading 109 } // end function operator<< 1 // Exercise Solution: Employee.h 2 // Employee abstract base class. 3 #ifndef EMPLOYEE_H 4 #define EMPLOYEE_H 6 #include <string> // C++ standard string class 7 #include "Date.h" // Date class definition 8 using namespace std; 9 10 class Employee 11 { 12 public: 13 Employee( const string &, const string &, const string &, 14 int, int, int ); 1 16 void setfirstname( const string & ); // set first name 17 string getfirstname() const; // return first name void setlastname( const string & ); // set last name 20 string getlastname() const; // return last name void setsocialsecuritynumber( const string & ); // set SSN 23 string getsocialsecuritynumber() const; // return SSN 24 2 void setbirthdate( int, int, int ); // set birthday 26 Date getbirthdate() const; // return birthday // pure virtual function makes Employee abstract base class 29 virtual double earnings() const = 0; // pure virtual 30 virtual void print() const; // virtual 31 private: 4

5 32 string firstname; 33 string lastname; 34 string socialsecuritynumber; 3 Date birthdate; // the Employee's birthday 36 }; // end class Employee #endif // EMPLOYEE_H 1 // Exercise Solution: Employee.cpp 2 // Abstract-base-class Employee member-function definitions. 3 // Note: No definitions are given for pure virtual functions. 4 #include <iostream> #include "Employee.h" // Employee class definition 6 using namespace std; 7 8 // constructor 9 Employee::Employee( const string &first, const string &last, 10 const string &ssn, int month, int day, int year ) 11 : firstname( first ), lastname( last ), socialsecuritynumber( ssn ), 12 birthdate( month, day, year ) 13 { 14 // empty body 1 } // end Employee constructor // set first name 18 void Employee::setFirstName( const string &first ) 19 { 20 firstname = first; 21 } // end function setfirstname // return first name 24 string Employee::getFirstName() const 2 { 26 return firstname; 27 } // end function getfirstname // set last name 30 void Employee::setLastName( const string &last ) 31 { 32 lastname = last; 33 } // end function setlastname 34 3 // return last name 36 string Employee::getLastName() const 37 {

6 38 return lastname; 39 } // end function getlastname // set social security number 42 void Employee::setSocialSecurityNumber( const string &ssn ) 43 { 44 socialsecuritynumber = ssn; // should validate 4 } // end function setsocialsecuritynumber // return social security number 48 string Employee::getSocialSecurityNumber() const 49 { 0 return socialsecuritynumber; 1 } // end function getsocialsecuritynumber 2 3 // set birthday 4 void Employee::setBirthDate( int month, int day, int year ) { 6 birthdate.setdate( month, day, year ); 7 } // end function setbirthdate 8 9 // return birthday 60 Date Employee::getBirthDate() const 61 { 62 return birthdate; 63 } // end function getbirthdate 64 6 // print Employee's information (virtual, but not pure virtual) 66 void Employee::print() const 67 { 68 cout << getfirstname() << ' ' << getlastname() 69 << "\nbirthday: " << getbirthdate() 70 << "\nsocial security number: " << getsocialsecuritynumber(); 71 } // end function print 1 // Exercise Solution: HourlyEmployee.h 2 // HourlyEmployee class definition. 3 #ifndef HOURLY_H 4 #define HOURLY_H 6 #include "Employee.h" // Employee class definition 7 8 class HourlyEmployee : public Employee 9 { 10 public: 6

7 11 static const int hoursperweek = 168; // hours in one week HourlyEmployee( const string &, const string &, 14 const string &, int, int, int, double = 0.0, double = 0.0 ); 1 16 void setwage( double ); // set hourly wage 17 double getwage() const; // return hourly wage void sethours( double ); // set hours worked 20 double gethours() const; // return hours worked // keyword virtual signals intent to override 23 virtual double earnings() const; // calculate earnings 24 virtual void print() const; // print HourlyEmployee object 2 private: 26 double wage; // wage per hour 27 double hours; // hours worked for week 28 }; // end class HourlyEmployee #endif // HOURLY_H 1 // Exercise Solution: HourlyEmployee.cpp 2 // HourlyEmployee class member-function definitions. 3 #include <iostream> 4 #include "HourlyEmployee.h" // HourlyEmployee class definition using namespace std; 6 7 // constructor 8 HourlyEmployee::HourlyEmployee( const string &first, const string &last, 9 const string &ssn, int month, int day, int year, 10 double hourlywage, double hoursworked ) 11 : Employee( first, last, ssn, month, day, year ) 12 { 13 setwage( hourlywage ); // validate hourly wage 14 sethours( hoursworked ); // validate hours worked 1 } // end HourlyEmployee constructor // set wage 18 void HourlyEmployee::setWage( double hourlywage ) 19 { 20 wage = ( hourlywage < 0.0? 0.0 : hourlywage ); 21 } // end function setwage // return wage 24 double HourlyEmployee::getWage() const 7

8 2 { 26 return wage; 27 } // end function getwage // set hours worked 30 void HourlyEmployee::setHours( double hoursworked ) 31 { 32 hours = ( ( ( hoursworked >= 0.0 ) && 33 ( hoursworked <= hoursperweek ) )? hoursworked : 0.0 ); 34 } // end function sethours 3 36 // return hours worked 37 double HourlyEmployee::getHours() const 38 { 39 return hours; 40 } // end function gethours // calculate earnings; 43 // override pure virtual function earnings in Employee 44 double HourlyEmployee::earnings() const 4 { 46 if ( gethours() <= 40 ) // no overtime 47 return getwage() * gethours(); 48 else 49 return 40 * getwage() + ( ( gethours() - 40 ) * getwage() * 1. ); 0 } // end function earnings 1 2 // print HourlyEmployee's information 3 void HourlyEmployee::print() const 4 { cout << "hourly employee: "; 6 Employee::print(); // code reuse 7 cout << "\nhourly wage: " << getwage() << 8 "; hours worked: " << gethours(); 9 } // end function print 1 // Exercise Solution: SalariedEmployee.h 2 // SalariedEmployee class derived from Employee. 3 #ifndef SALARIED_H 4 #define SALARIED_H 6 #include "Employee.h" // Employee class definition 7 8 class SalariedEmployee : public Employee 9 { 8

9 10 public: 11 SalariedEmployee( const string &, const string &, 12 const string &, int, int, int, double = 0.0 ); void setweeklysalary( double ); // set weekly salary 1 double getweeklysalary() const; // return weekly salary // keyword virtual signals intent to override 18 virtual double earnings() const; // calculate earnings 19 virtual void print() const; // print SalariedEmployee object 20 private: 21 double weeklysalary; // salary per week 22 }; // end class SalariedEmployee #endif // SALARIED_H 1 // Exercise Solution: SalariedEmployee.cpp 2 // SalariedEmployee class member-function definitions. 3 #include <iostream> 4 #include "SalariedEmployee.h" // SalariedEmployee class definition using namespace std; 6 7 // constructor 8 SalariedEmployee::SalariedEmployee( const string &first, 9 const string &last, const string &ssn, int month, int day, int year, 10 double salary ) 11 : Employee( first, last, ssn, month, day, year ) 12 { 13 setweeklysalary( salary ); 14 } // end SalariedEmployee constructor 1 16 // set salary 17 void SalariedEmployee::setWeeklySalary( double salary ) 18 { 19 weeklysalary = ( salary < 0.0 )? 0.0 : salary; 20 } // end function setweeklysalary // return salary 23 double SalariedEmployee::getWeeklySalary() const 24 { 2 return weeklysalary; 26 } // end function getweeklysalary // calculate earnings; 29 // override pure virtual function earnings in Employee 9

10 30 double SalariedEmployee::earnings() const 31 { 32 return getweeklysalary(); 33 } // end function earnings 34 3 // print SalariedEmployee's information 36 void SalariedEmployee::print() const 37 { 38 cout << "salaried employee: "; 39 Employee::print(); // reuse abstract base-class print function 40 cout << "\nweekly salary: " << getweeklysalary(); 41 } // end function print 1 // Exercise Solution: CommissionEmployee.h 2 // CommissionEmployee class derived from Employee. 3 #ifndef COMMISSION_H 4 #define COMMISSION_H 6 #include "Employee.h" // Employee class definition 7 8 class CommissionEmployee : public Employee 9 { 10 public: 11 CommissionEmployee( const string &, const string &, 12 const string &, int, int, int, double = 0.0, double = 0.0 ); void setcommissionrate( double ); // set commission rate 1 double getcommissionrate() const; // return commission rate void setgrosssales( double ); // set gross sales amount 18 double getgrosssales() const; // return gross sales amount // keyword virtual signals intent to override 21 virtual double earnings() const; // calculate earnings 22 virtual void print() const; // print CommissionEmployee object 23 private: 24 double grosssales; // gross weekly sales 2 double commissionrate; // commission percentage 26 }; // end class CommissionEmployee #endif // COMMISSION_H 1 // Exercise Solution: CommissionEmployee.cpp 2 // CommissionEmployee class member-function definitions. 10

11 3 #include <iostream> 4 #include "CommissionEmployee.h" // CommissionEmployee class definition using namespace std; 6 7 // constructor 8 CommissionEmployee::CommissionEmployee( const string &first, 9 const string &last, const string &ssn, int month, int day, int year, 10 double sales, double rate ) 11 : Employee( first, last, ssn, month, day, year ) 12 { 13 setgrosssales( sales ); 14 setcommissionrate( rate ); 1 } // end CommissionEmployee constructor // set commission rate 18 void CommissionEmployee::setCommissionRate( double rate ) 19 { 20 commissionrate = ( ( rate > 0.0 && rate < 1.0 )? rate : 0.0 ); 21 } // end function setcommissionrate // return commission rate 24 double CommissionEmployee::getCommissionRate() const 2 { 26 return commissionrate; 27 } // end function getcommissionrate // set gross sales amount 30 void CommissionEmployee::setGrossSales( double sales ) 31 { 32 grosssales = ( ( sales < 0.0 )? 0.0 : sales ); 33 } // end function setgrosssales 34 3 // return gross sales amount 36 double CommissionEmployee::getGrossSales() const 37 { 38 return grosssales; 39 } // end function getgrosssales // calculate earnings; 42 // override pure virtual function earnings in Employee 43 double CommissionEmployee::earnings() const 44 { 4 return getcommissionrate() * getgrosssales(); 46 } // end function earnings // print CommissionEmployee's information 11

12 49 void CommissionEmployee::print() const 0 { 1 cout << "commission employee: "; 2 Employee::print(); // code reuse 3 cout << "\ngross sales: " << getgrosssales() 4 << "; commission rate: " << getcommissionrate(); } // end function print 1 // Exercise Solution: BasePlusCommissionEmployee.h 2 // BasePlusCommissionEmployee class derived from CommissionEmployee. 3 #ifndef BASEPLUS_H 4 #define BASEPLUS_H 6 #include "CommissionEmployee.h" // CommissionEmployee class definition 7 8 class BasePlusCommissionEmployee : public CommissionEmployee 9 { 10 public: 11 BasePlusCommissionEmployee( const string &, const string &, 12 const string &, int, int, int, double = 0.0, double = 0.0, 13 double = 0.0 ); 14 1 void setbasesalary( double ); // set base salary 16 double getbasesalary() const; // return base salary // keyword virtual signals intent to override 19 virtual double earnings() const; // calculate earnings 20 virtual void print() const; // print BasePlusCommissionEmployee object 21 private: 22 double basesalary; // base salary per week 23 }; // end class BasePlusCommissionEmployee 24 2 #endif // BASEPLUS_H 1 // Exercise Solution: BasePlusCommissionEmployee.cpp 2 // BasePlusCommissionEmployee member-function definitions. 3 #include <iostream> 4 // BasePlusCommissionEmployee class definition 6 #include "BasePlusCommissionEmployee.h" 7 using namespace std; 8 9 // constructor 10 BasePlusCommissionEmployee::BasePlusCommissionEmployee( 12

13 11 const string &first, const string &last, const string &ssn, 12 int month, int day, int year, double sales, 13 double rate, double salary ) 14 : CommissionEmployee( first, last, ssn, month, day, year, sales, rate ) 1 { 16 setbasesalary( salary ); // validate and store base salary 17 } // end BasePlusCommissionEmployee constructor // set base salary 20 void BasePlusCommissionEmployee::setBaseSalary( double salary ) 21 { 22 basesalary = ( ( salary < 0.0 )? 0.0 : salary ); 23 } // end function setbasesalary 24 2 // return base salary 26 double BasePlusCommissionEmployee::getBaseSalary() const 27 { 28 return basesalary; 29 } // end function getbasesalary // calculate earnings; 32 // override pure virtual function earnings in Employee 33 double BasePlusCommissionEmployee::earnings() const 34 { 3 return getbasesalary() + CommissionEmployee::earnings(); 36 } // end function earnings // print BasePlusCommissionEmployee's information 39 void BasePlusCommissionEmployee::print() const 40 { 41 cout << "base-salaried "; 42 CommissionEmployee::print(); // code reuse 43 cout << "; base salary: " << getbasesalary(); 44 } // end function print 1 // Exercise Solution: ex13_12.cpp 2 // Processing Employee derived-class objects polymorphically. 3 #include <iostream> 4 #include <iomanip> #include <vector> 6 #include <typeinfo> 7 #include <ctime> 8 9 // include definitions of classes in Employee hierarchy 10 #include "Employee.h" 13

14 11 #include "SalariedEmployee.h" 12 #include "HourlyEmployee.h" 13 #include "CommissionEmployee.h" 14 #include "BasePlusCommissionEmployee.h" 1 using namespace std; int determinemonth(); // prototype of function that returns current month int main() 20 { 21 // set floating-point output formatting 22 cout << fixed << setprecision( 2 ); // create vector of four base-class pointers 2 vector < Employee * > employees( 4 ); // initialize vector with Employees 28 employees[ 0 ] = new SalariedEmployee( 29 "John", "Smith", " ", 6, 1, 1944, 800 ); 30 employees[ 1 ] = new HourlyEmployee( 31 "Karen", "Price", " ", 12, 29, 1960, 16.7, 40 ); 32 employees[ 2 ] = new CommissionEmployee( 33 "Sue", "Jones", " ", 9, 8, 194, 10000,.06 ); 34 employees[ 3 ] = new BasePlusCommissionEmployee( 3 "Bob", "Lewis", " ", 3, 2, 196, 000,.04, 300 ); int month = determinemonth(); cout << "Employees processed polymorphically via dynamic binding:\n\n"; for ( size_t i = 0; i < employees.size(); i++ ) 42 { 43 employees[ i ]->print(); // output employee information 44 cout << endl; 4 46 // downcast pointer 47 BasePlusCommissionEmployee *derivedptr = 48 dynamic_cast < BasePlusCommissionEmployee * > 49 ( employees[ i ] ); 0 1 // determine whether element points to base-salaried 2 // commission employee 3 if ( derivedptr!= 0 ) // 0 if not a BasePlusCommissionEmployee 4 { double oldbasesalary = derivedptr->getbasesalary(); 6 cout << "old base salary: $" << oldbasesalary << endl; 14

15 7 derivedptr->setbasesalary( 1.10 * oldbasesalary ); 8 cout << "new base salary with 10% increase is: $" 9 << derivedptr->getbasesalary() << endl; 60 } // end if // get current employee's birthday 63 Date birthday = employees[ i ]->getbirthdate(); 64 6 // if current month is employee's birthday month, add $100 to salary 66 if ( birthday.getmonth() == month ) 67 cout << "HAPPY BIRTHDAY!\nearned $" 68 << ( employees[ i ]->earnings() ) << endl; 69 else 70 cout << "earned $" << employees[ i ]->earnings() << endl; cout << endl; 73 } // end for 74 7 // release objects pointed to by vector 抯 '92selements 76 for ( size_t j = 0; j < employees.size(); j++ ) 77 { 78 // output class name 79 cout << "deleting object of " 80 << typeid( *employees[ j ] ).name() << endl; delete employees[ j ]; 83 } // end for 84 } // end main 8 86 // Determine the current month using standard library functions of ctime 87 int determinemonth() 88 { 89 time_t currenttime; 90 char monthstring[ 3 ]; 91 time( &currenttime ); 92 strftime( monthstring, 3, "%m", localtime( &currenttime ) ); 93 return atoi( monthstring ); 94 } // end function determinemonth 1

16 Ex // Solution Solution: Account.h 2 // Definition of Account class. 3 #ifndef ACCOUNT_H 4 #define ACCOUNT_H 6 class Account 7 { 8 public: 9 Account( double ); // constructor initializes balance 10 virtual void credit( double ); // add an amount to the account balance 11 virtual bool debit( double ); // subtract an amount from the balance 12 void setbalance( double ); // sets the account balance 13 double getbalance(); // return the account balance 14 private: 1 double balance; // data member that stores the balance 16 }; // end class Account #endif 1 // Exercise Solution: Account.cpp 2 // Member-function definitions for class Account. 3 #include <iostream> 4 #include "Account.h" // include definition of class Account using namespace std; 6 7 // Account constructor initializes data member balance 8 Account::Account( double initialbalance ) 9 { 10 // if initialbalance is greater than or equal to 0.0, set this value 11 // as the balance of the Account 12 if ( initialbalance >= 0.0 ) 13 balance = initialbalance; 14 else // otherwise, output message and set balance to { 16 cout << "Error: Initial balance cannot be negative." << endl; 17 balance = 0.0; 18 } // end if...else 19 } // end Account constructor // credit (add) an amount to the account balance 22 void Account::credit( double amount ) 23 { 24 balance = balance + amount; // add amount to balance 2 } // end function credit 16

17 26 27 // debit (subtract) an amount from the account balance 28 // return bool indicating whether money was debited 29 bool Account::debit( double amount ) 30 { 31 if ( amount > balance ) // debit amount exceeds balance 32 { 33 cout << "Debit amount exceeded account balance." << endl; 34 return false; 3 } // end if 36 else // debit amount does not exceed balance 37 { 38 balance = balance - amount; 39 return true; 40 } // end else 41 } // end function debit // set the account balance 44 void Account::setBalance( double newbalance ) 4 { 46 balance = newbalance; 47 } // end function setbalance // return the account balance 0 double Account::getBalance() 1 { 2 return balance; 3 } // end function getbalance 1 // Exercise Solution: CheckingAccount.h 2 // Definition of CheckingAccount class. 3 #ifndef CHECKING_H 4 #define CHECKING_H 6 #include "Account.h" // Account class definition 7 8 class CheckingAccount : public Account 9 { 10 public: 11 // constructor initializes balance and transaction fee 12 CheckingAccount( double, double ); virtual void credit( double ); // redefined credit function 1 virtual bool debit( double ); // redefined debit function 16 private: 17

18 17 double transactionfee; // fee charged per transaction // utility function to charge fee 20 void chargefee(); 21 }; // end class CheckingAccount #endif 1 // Exercise Solution: CheckingAccount.cpp 2 // Member-function definitions for class CheckingAccount. 3 #include <iostream> 4 #include "CheckingAccount.h" // CheckingAccount class definition using namespace std; 6 7 // constructor initializes balance and transaction fee 8 CheckingAccount::CheckingAccount( double initialbalance, double fee ) 9 : Account( initialbalance ) // initialize base class 10 { 11 transactionfee = ( fee < 0.0 )? 0.0 : fee; // set transaction fee 12 } // end CheckingAccount constructor // credit (add) an amount to the account balance and charge fee 1 void CheckingAccount::credit( double amount ) 16 { 17 Account::credit( amount ); // always succeeds 18 chargefee(); 19 } // end function credit // debit (subtract) an amount from the account balance and charge fee 22 bool CheckingAccount::debit( double amount ) 23 { 24 bool success = Account::debit( amount ); // attempt to debit 2 26 if ( success ) // if money was debited, charge fee and return true 27 { 28 chargefee(); 29 return true; 30 } // end if 31 else // otherwise, do not charge fee and return false 32 return false; 33 } // end function debit 34 3 // subtract transaction fee 36 void CheckingAccount::chargeFee() 37 { 18

19 38 Account::setBalance( getbalance() - transactionfee ); 39 cout << "$" << transactionfee << " transaction fee charged." << endl; 40 } // end function chargefee 1 // Exercise Solution: SavingsAccount.h 2 // Definition of SavingsAccount class. 3 #ifndef SAVINGS_H 4 #define SAVINGS_H 6 #include "Account.h" // Account class definition 7 8 class SavingsAccount : public Account 9 { 10 public: 11 // constructor initializes balance and interest rate 12 SavingsAccount( double, double ); double calculateinterest(); // determine interest owed 1 private: 16 double interestrate; // interest rate (percentage) earned by account 17 }; // end class SavingsAccount #endif 1 // Exercise Solution: SavingsAccount.cpp 2 // Member-function definitions for class SavingsAccount. 3 4 #include "SavingsAccount.h" // SavingsAccount class definition 6 // constructor initializes balance and interest rate 7 SavingsAccount::SavingsAccount( double initialbalance, double rate ) 8 : Account( initialbalance ) // initialize base class 9 { 10 interestrate = ( rate < 0.0 )? 0.0 : rate; // set interestrate 11 } // end SavingsAccount constructor // return the amount of interest earned 14 double SavingsAccount::calculateInterest() 1 { 16 return getbalance() * interestrate; 17 } // end function calculateinterest 1 // Exercise Solution: ex13_16.cpp 19

20 2 // Processing Accounts polymorphically. 3 #include <iostream> 4 #include <iomanip> #include <vector> 6 #include "Account.h" // Account class definition 7 #include "SavingsAccount.h" // SavingsAccount class definition 8 #include "CheckingAccount.h" // CheckingAccount class definition 9 using namespace std; int main() 12 { 13 // create vector accounts 14 vector < Account * > accounts( 4 ); 1 16 // initialize vector with Accounts 17 accounts[ 0 ] = new SavingsAccount( 2.0,.03 ); 18 accounts[ 1 ] = new CheckingAccount( 80.0, 1.0 ); 19 accounts[ 2 ] = new SavingsAccount( 200.0,.01 ); 20 accounts[ 3 ] = new CheckingAccount( 400.0,. ); cout << fixed << setprecision( 2 ); // loop through vector, prompting user for debit and credit amounts 2 for ( size_t i = 0; i < accounts.size(); i++ ) 26 { 27 cout << "Account " << i + 1 << " balance: $" 28 << accounts[ i ]->getbalance(); double withdrawalamount = 0.0; 31 cout << "\nenter an amount to withdraw from Account " << i << ": "; 33 cin >> withdrawalamount; 34 accounts[ i ]->debit( withdrawalamount ); // attempt to debit 3 36 double depositamount = 0.0; 37 cout << "Enter an amount to deposit into Account " << i << ": "; 39 cin >> depositamount; 40 accounts[ i ]->credit( depositamount ); // credit amount to Account // downcast pointer 43 SavingsAccount *savingsaccountptr = 44 dynamic_cast < SavingsAccount * > ( accounts[ i ] ); 4 46 // if Account is a SavingsAccount, calculate and add interest 47 if ( savingsaccountptr!= 0 ) 20

21 48 { 49 double interestearned = savingsaccountptr->calculateinterest(); 0 cout << "Adding $" << interestearned << " interest to Account " 1 << i + 1 << " (a SavingsAccount)" << endl; 2 savingsaccountptr->credit( interestearned ); 3 } // end if 4 cout << "Updated Account " << i + 1 << " balance: $" 6 << accounts[ i ]->getbalance() << "\n\n"; 7 } // end for 8 } // end main 21