【正文】 de // include definition of class Date from // Date constructor that initializes the three data members。 // the day of the date int year。 // set year int getYear()。 // set month int getMonth()。 cout () () : $ monthlySalary2 * 12 endl。 // retrieve and display employee139。 ( monthlySalary2 * )。 // retrieve and display employee239。 yearly salaries: endl。include // include definition of class Employee// function main begins program executionint main(){ // create two Employee objects Employee employee1( Lisa, Roberts, 4500 )。 // set monthlySalary to salary if ( salary = 0 ) // if salary is not positive monthlySalary = 0。} // end function getFirstName// set last namevoid Employee::setLastName( string name ){ lastName = name。 // store first name setLastName( last )。 // Employee39。 // Employee39。 // set last name string getLastName()。// Employee class definitionclass Employee {public: Employee( string, string, int )。 cout Price per item: $ () endl。 cout \nInvoice data members modified.\n\n。 // modify the invoice data members ( 123456 )。 cout Part description: () endl。using std::cin。 // set pricePerItem to 0 cout \npricePerItem cannot be negative. pricePerItem set to 0.\n。 } // end if} // end function setQuantity// get quantityint Invoice::getQuantity(){ return quantity。} // end function getPartDescription// set quantity。 // validate and store pricePerItem} // end Invoice constructor// set part numbervoid Invoice::setPartNumber( string number ){ partNumber = number。s four data membersInvoice::Invoice( string number, string description, int count, int price ){ setPartNumber( number )。 // price per item}。 private: string partNumber。 // quantity int getQuantity()。 // part number string getPartNumber()。 return 0。 // obtain user input cout \nattempting to subtract withdrawalAmount from account2 balance\n\n。 // try to subtract from account1 // display balances cout account1 balance: $ () endl。 // stores withdrawal amount read from user cout \nEnter withdrawal amount for account1: 。 // create Account object Account account2( 25 )。 // gives the value of balance to the calling function} // end function getBalance測(cè)試函數(shù)：include iostreamusing std::cout。} // end Account constructor// credit (add) an amount to the account balancevoid Account::credit( int amount ){ balance = balance + amount。include // include definition of class Account// Account constructor initializes data member balanceAccount::Account( int initialBalance ){ balance = 0。 // return the account balanceprivate: int balance。 // indicate successful termination} // end main類定義：class Account{public: Account( int )。 // display new value of instructorName cout new gradeBook instructor name is: () \n\n。// include definition of class GradeBook from include // function main begins program executionint main(){ // create a GradeBook object。 // display the instructor39。} // end function getCourseName// function to set the instructor namevoid GradeBook::setInstructorName( string name ){ instructorName = name。include // constructor initializes courseName and instructorName // with strings supplied as argumentsGradeBook::GradeBook( string course, string instructor ){ setCourseName( course )。 // course name for this GradeBook string instructorName。 // function to retrieve the course name void setInstructorName( string )。C++ 大學(xué)基礎(chǔ)教程 課后答案（DEITEL）版GradeBook類定義：include string // program uses C++ standard string classusing std::string。 // function to set the course name string getCourseName()。 // display wele message and instructor nameprivate: string courseName。using std::endl。 // store the course name} // end function setCourseName// function to retrieve the course namestring GradeBook::getCourseName(){ return courseName。s namevoid GradeBook::displayMessage(){ // display a wele message containing the course name cout Wele to the grade book for\n getCourseName() ! endl。 using std::endl。 // modify the instructorName using set function ( Assistant Professor Bates )。 return 0。 // subtract an amount from the account balance int getBalance()。using std::endl。 // if initialBalance is negative, print error message if ( initialBalance 0 ) cout Error: Initial balance cannot be negative.\n endl。} // end function debit// return the account balanceint Account::getBalance(){ return balance。// include definition of class Account from include // function main begins program executionint main(){ Account account1( 50 )。 int withdrawalAmount。 ( withdrawalAmount )。 // prompt cin withdrawalAmount。 cout account2 balance: $ () endl。 // set and get functions for the four data members void setPartNumber( string )。 void setQuantity( int )。 // calculates invoice amount by multiplying quantity x price per item int getInvoiceAmount()。 // how many of the items are being sold int pricePerItem。// include definition of class Invoice from include // Invoice constructor initializes the class39。 // validate and store quantity setPricePerItem( price )。 // no validation needed} // end function setPartDescription// get part descriptionstring Invoice::getPartDescription(){ return partDescription。 // set quantity to 0 cout \nquantity cannot be negative. quantity set to 0.\n。 // set pricePerItem to price if ( price = 0 ) // if price is not positive { pricePerItem = 0。} // end function getInvoiceA