面向对象的C++程序设计 第六版 课后习题答案 第十五章

Chapter15INHERITANCE1.Solutions to and Remarks on Selected Programming Problems1.Derive class Administrator from class SalariedEmployeePlease note an error in the statement of Programming Project1:In the requirement for a member function called"print"which the problem says"...output the programmer's data to the screen."This should read"...output the administrator's data to the screen."Remarks:Ideally the member functions in the base class Employee that are going to be declared in derived classes should be declared"pure virtual"where the body{...}is replaced by=0;. This results in the compiler forcing any directly derived function to define a member with this signature,which,presumably is better suited than any base class member function will be.Print check may well be different for each derived class.The member function void give_raise(double)could be different as well.Regarding the function that reads the administrator's data,note that a new administrator's data will be entered in response to the base class Employee and derive class SalariedEmployee inquiries,then the administrator class function will make inquiry.My design and implementation follow:Title:Derive class AdministratorWrite a program using classes from Display15.1-15.4Define class Administrator which derives publicly from class SalariedEmployee. Explain why there is a need to change private:to protected:Answer:To allow the member functions inherited class member to see these data members.Additional protected members required are:string titleadministrator's title(CEO,Director etc.)string responsibility(production,accounting,personnel) string supervisor(name of immediate supervisor)double annual_salary(if not already added in the self test exercise)Additional public members required are:A function to change name of immediate supervisorvoid change_supervisor(string new_super);A function for reading all of a new administrator's data from the keyboard.Note that the data inherited from class Employee will already be fetched by required base class constructors.class constructors.void get_admin_data();function to output administrator's data to the screenvoid print();a function to print a check with appropriate notations on the checkvoid print_check()//file:ch15p1.h//This is the INTERFACE for class Administrator which//inherits from class Employee and class SalariedEmployee#ifndef ADMINISTRATOR_H#define ADMINISTRATOR_H#include"employee.h"//from Display15.1 namespace employeessavitch{class Administrator:public SalariedEmployee{public:Administrator();Administrator(string aTitle,string aResponsibilty,string aSupervisor);//change name of immediate supervisorvoid change_supervisor(string new_super);//Read a new administrator's data from the keyboard.void get_admin_data();//outputs administrator's data to the screenvoid print();//prints a check with appropriate notations on the checkvoid print_check();void give_raise(double amount);protected:string title;//administrator's title//(CEO,Director,Vice President)string responsibility;//production,accounting, personnelstring supervisor;//name of immediate supervisor long double annual_salary;//if not added in the self//test exercise};}#endif//File://Chapter15Programming Project1//Implementation for the Administrator derived class#include"employee.h"//display15.2#include"ch15p1.h"//Previous header file#include<iostream>namespace employeesavitch{voidAdministrator::give_raise(double amount){annual_salary+=amount;}Administrator::Administrator():SalariedEmployee(){using namespace std;cout<<"\nAdministrative Employee data"<<"is being entered:\n\n";get_admin_data();}Administrator::Administrator(string aTitle,string aResponsibilty,string aSupervisor):SalariedEmployee(),title(aTitle),responsibility(aResponsibilty),supervisor(aSupervisor){//deliberately empty}//change name of immediate supervisorvoid Administrator::change_supervisor(string new_super) {supervisor=new_super;}//Reading all of a new administrator's data from the//keyboard.void Administrator::get_admin_data(){using namespace std;cout<<"Enter title,followed by return:\n";getline(cin,title);cout<<"\nEnter area of responsibility"<<"followed by return:\n";getline(cin,responsibility);cout<<"\nEnter supervisor's name,"<<"followed by return:\n";getline(cin,supervisor);cout<<"\nEnter salary followed by return:\n";cin>>annual_salary;}//outputs administrator's data to the screenvoid Administrator::print(){using namespace std;cout<<"\n\nprinting data\n";cout<<"Name:"<<name<<endl;cout<<"Annual Salary:$"<<annual_salary<<endl; cout<<"Social Security Number:"<<ssn<<endl; cout<<"Title:";cout<<title<<endl;cout<<"Responsibility:";cout<<responsibility<<endl;cout<<"supervisor:";cout<<supervisor<<endl;cout.setf(ios::showpoint);cout.setf(ios::fixed);cout.precision(2);cout<<"Annual Salary:";cout<<annual_salary<<endl;}//prints a check with appropriate notations on the check void Administrator::print_check(){using namespace std;long double monthly_pay=annual_salary/12;cout<<"\n__________________________________________________\n"; cout<<"Pay to the order of"<<name<<endl;cout.setf(ios::showpoint);cout.setf(ios::fixed);cout.precision(2);cout<<"The sum of$"<<monthly_pay<<"Dollars\n";cout<<"_________________________________________________\n";cout<<"Check Stub NOT NEGOTIABLE\n";cout<<"Employee Number:"<<ssn<<endl;cout<<"Administrative Employee.\n";cout<<"_________________________________________________\n"; }}//end namespace employeesavitch2.Add Temporary,Administrative,Permenant etc classifications to15.1…No solution is provided for this problem.3.Derive class Doctor from SalariedEmployeeNo solution is provided for this problem.4.Create a base class vehicleNo solution is provided for this problem.5.Define classes Patient and BillingNo solution is provided for this problem.6.No Solution Provided.7.Implement a graphics SystemImplement a graphics System that has classes for various figures:rectangles,squares, triangles,circles,etc.A rectangle has data members height,width,and center point.A square has center point and an edge.A circle has data members center and radius.The several specific shape classes are derived from a common class,Figure. Implement only Rectangle and Triangle classes.Derive them from Figure. Each class has stubs for erase and draw.The class Figure has member function center that calls erase and draw.The functions erase and draw are only stubs,consequently center does little but call erase and draw.Add a message to center announcing that it is being called.There are3parts:a)Write the class definitions using no virtual pile and test.b)Make the base class member functions pile and test.c)Explain the differences.Use the following main function:#include<iostream>#include"figure.h"#include"rectangle.h"#include"triangle.h"using std::cout;int main(){Triangle tri;tri.draw();cout<<"\nDerived class Triangle object calling"<<"center().\n";tri.center();Rectangle rect;rect.draw();cout<<"\nDerived class Rectangle object calling"<<"center().\n";rect.center();return0;}Solution:I have used no member variables,as they serve no function in this part of the exercise.//figure.h#include<iostream>using namespace std;#ifndef PROTECT_FIGURE_H#define PROTECT_FIGURE_Hclass Figure{public://virtual//Uncomment to make erase()a virtual function void erase();//virtual//Uncomment to make draw()a virtual function void draw();void center(){cout<<"member function center called"<<endl;erase();draw();}};#endif//File:figure.cpp#include"figure.h"void Figure::erase(){cout<<"Figure::erase()"<<endl; }void Figure::draw(){cout<<"Figure::draw()"<<endl; }//end of file figure.cpp//rectangle.h#include<iostream>#include"figure.h"using namespace std;class Rectangle:public Figure{public:void erase();void draw();};void Rectangle::erase(){cout<<"Rectangle::erase()"<<endl; }void Rectangle::draw(){cout<<"Rectangle::draw()"<<endl; }//triangle.h#include<iostream>#include"figure.h"using namespace std;class Triangle:public Figure{public:void draw();void erase();};void Triangle::draw(){cout<<"Triangle::draw()"<<endl; }void Triangle::erase(){cout<<"Triangle::erase()"<<endl;}//ch13p1App.cpp#include<iostream>#include"figure.h"#include"rectangle.h"#include"triangle.h"using std::cout;int main(){Triangle tri;tri.draw();cout<<"\nIn main,Derived class Triangle object calling"<<"center().\n";tri.center();Rectangle rect;rect.draw();cout<<"\nIn main,Derived class Rectangle object calling"<<"center().\n";rect.center();return0;}A trial run follows:With NON virtual draw()and erase()Triangle::draw()In main,Derived class Triangle object calling center(). member function center calledFigure::erase()Figure::draw()Rectangle::draw()In main,Derived class Rectangle object calling center(). member function center calledFigure::erase()Figure::draw()With virtual draw()and erase():Triangle::draw()In main,Derived class Triangle object calling center(). member function center calledTriangle::erase()Triangle::draw()Rectangle::draw()Explanation of differenceThe differences are due solely to the presence or absence of the keyword virtual in the base class figure.8.Flesh out Problem7Give new definitions and member functions for Figure::center,Figure::draw, Figure::erase,Triangle::draw,Triangle::erase, Rectangle::draw,Rectangle::erase,so that the draw functions actually draw figures on the screen using asterisks(*).For the erase function,clear the screen.No solution to this part is provided.9.No Solution Provided.10.//****************************************************************////Ch15Proj10.cpp////This program uses inheritance to simulate retrieving the contents //of a RFID shipping container and a manual shipping container.//****************************************************************#include<iostream>#include<vector>#include<string>#include<sstream>using namespace std;//*************************Begin ShippingContainer Classclass ShippingContainer{public:ShippingContainer();ShippingContainer(int newID);int getID();void setID(int newID);virtual string getManifest();private:int id;};//======================//ShippingContainer::ShippingContainer//Constructors//======================ShippingContainer::ShippingContainer(){id=-1;}ShippingContainer::ShippingContainer(int newID){id=newID;}//======================//ShippingContainer::getID//Returns the ID number//======================int ShippingContainer::getID(){return id;}//======================//ShippingContainer::setID//Sets the ID number//======================void ShippingContainer::setID(int newID){id=newID;}//======================//ShippingContainer::getManifest//Returns empty contents//======================string ShippingContainer::getManifest(){return"";}//*************************Begin ManualShippingContainer Classclass ManualShippingContainer:public ShippingContainer{public:ManualShippingContainer(int newID);void setManifest(string s);virtual string getManifest();private:string contents;};//======================//ManualShippingContainer::ManualShippingContainer//Constructor//====================== ManualShippingContainer::ManualShippingContainer(int newID): ShippingContainer(newID){}//======================//ManualShippingContainer::setManifest//Sets the manifest for this container//======================void ManualShippingContainer::setManifest(string s){contents=s;}//======================//ManualShippingContainer::getManifest//Returns the manifest for this container//======================string ManualShippingContainer::getManifest(){return contents;}//*************************Begin RFIDShippingContainer Classclass RFIDShippingContainer:public ShippingContainer{public:RFIDShippingContainer(int newID);void add(string s);virtual string getManifest();private:vector<string>contents;vector<int>count;int search(string s);};//======================//RFIDShippingContainer::RFIDShippingContainer//Constructor//======================RFIDShippingContainer::RFIDShippingContainer(int newID):ShippingContainer(newID){}//======================//RFIDShippingContainer::search//Search the vector for duplicates and if found//returns the index,or-1if not found//======================int RFIDShippingContainer::search(string s){int i;for(i=0;i<contents.size();i++){if(contents[i]==s)return i;}return-1;}//======================//RFIDShippingContainer::add//Adds a new string to the manifest vector.//======================void RFIDShippingContainer::add(string s){int i;i=search(s);if(i==-1){contents.push_back(s);//Add itemcount.push_back(1);//One occurrence of this item }else{count[i]++;//Add to occurrences of this item }}//======================//RFIDShippingContainer::getManifest//Returns the manifest for this container//by scanning through the vector//======================string RFIDShippingContainer::getManifest(){string s="";int i;for(i=0;i<contents.size();i++){//Convert number to string using stringstreamstringstream converter;converter<<count[i];s+=converter.str()+""+contents[i]+".";}return s;}//======================//main function//======================int main(){//Variable declarations with test data ShippingContainer*containers[6]; ManualShippingContainer m1(100),m2(200),m3(300); RFIDShippingContainer r1(400),r2(500),r3(600);m1.setManifest("1000diapers");m2.setManifest("1000candy bars.500toilet paper.");m3.setManifest("500books.");r1.add("apples");r1.add("apples");r1.add("cookies");r2.add("pineapple");r2.add("pears");r2.add("pineapple");r2.add("pears");r3.add("chocolate bars");r3.add("chocolate bars");r3.add("chocolate bars");//Store containers in the arraycontainers[0]=&m1;containers[1]=&m2;containers[2]=&m3;containers[3]=&r1;containers[4]=&r2;containers[5]=&r3;//Loop to output contents of the containersfor(int i=0;i<6;i++){cout<<"Container"<<containers[i]->getID()<<"contains"<<containers[i]->getManifest()<<endl; }return0;}11.//**************************************************************** ////Ch15Proj11.cpp////This program simulates a2D world with predators and prey.//The predators(doodlebugs)and prey(ants)inherit from the//Organism class that keeps track of basic information about each //critter(time ticks since last bred,position in the world).////The2D world is implemented as a separate class,World,//that contains a2D array of pointers to type Organism.////Normally the classes would be defined in separate files,but//they are all included here for ease of use with CodeMate.//****************************************************************#include<iostream>#include<string>#include<vector>#include<cstdlib>#include<time.h>using namespace std;const int WORLDSIZE=20;const int INITIALANTS=100;const int INITIALBUGS=5;const int DOODLEBUG=1;const int ANT=2;const int ANTBREED=3;const int DOODLEBREED=8;const int DOODLESTARVE=3;//Forward declaration of Organism classes so we can reference it//in the World classclass Organism;class Doodlebug;class Ant;//==========================================//The World class stores data about the world by creating a//WORLDSIZE by WORLDSIZE array of type Organism.//NULL indicates an empty spot,otherwise a valid object//indicates an ant or doodlebug.To determine which,//invoke the virtual function getType of Organism that should return //ANT if the class is of type ant,and DOODLEBUG otherwise.//==========================================class World{friend class Organism;//Allow Organism to access grid friend class Doodlebug;//Allow Organism to access grid friend class Ant;//Allow Organism to access grid public:World();~World();Organism*getAt(int x,int y);void setAt(int x,int y,Organism*org);void Display();void SimulateOneStep();private:Organism*grid[WORLDSIZE][WORLDSIZE];};//==========================================//Definition for the Organism base class.//Each organism has a reference back to//the World object so it can move itself//about in the world.//==========================================class Organism{friend class World;//Allow world to affect organism public:Organism();Organism(World*world,int x,int y);~Organism();virtual void breed()=0;//Whether or not to breedvirtual void move()=0;//Rules to move the crittervirtual int getType()=0;//Return if ant or doodlebugvirtual bool starve()=0;//Determine if organism starves protected:int x,y;//Position in the worldbool moved;//Bool to indicate if moved this turnint breedTicks;//Number of ticks since breeding World*world;};//======================//World constructor,destructor//These classes initialize the array and//releases any classes created when destroyed.//======================World::World(){//Initialize world to empty spacesint i,j;for(i=0;i<WORLDSIZE;i++){for(j=0;j<WORLDSIZE;j++){grid[i][j]=NULL;}}}World::~World(){//Release any allocated memoryint i,j;for(i=0;i<WORLDSIZE;i++){for(j=0;j<WORLDSIZE;j++){if(grid[i][j]!=NULL)delete(grid[i][j]);}}}//======================//getAt//Returns the entry stored in the grid array at x,y//======================Organism*World::getAt(int x,int y){if((x>=0)&&(x<WORLDSIZE)&&(y>=0)&&(y<WORLDSIZE)) return grid[x][y];return NULL;}//======================//setAt//Sets the entry at x,y to the//value passed in.Assumes that//someone else is keeping track of//references in case we overwrite something//that is not NULL(so we don't have a memory leak)//======================void World::setAt(int x,int y,Organism*org){if((x>=0)&&(x<WORLDSIZE)&&(y>=0)&&(y<WORLDSIZE)){grid[x][y]=org;}}//======================//Display//Displays the world in es o for ant,X for doodlebug. //======================void World::Display(){int i,j;cout<<endl<<endl;for(j=0;j<WORLDSIZE;j++){for(i=0;i<WORLDSIZE;i++){if(grid[i][j]==NULL)cout<<".";else if(grid[i][j]->getType()==ANT)cout<<"o";else cout<<"X";}cout<<endl;}}//======================//SimulateOneStep//This is the main routine that simulates one turn in the world.//First,a flag for each organism is used to indicate if it has moved. //This is because we iterate through the grid starting from the top//looking for an organism to move.If one moves down,we don't want//to move it again when we reach it.//First move doodlebugs,then ants,and if they are still alive then//we breed them.//======================void World::SimulateOneStep(){int i,j;//First reset all organisms to not movedfor(i=0;i<WORLDSIZE;i++)for(j=0;j<WORLDSIZE;j++){if(grid[i][j]!=NULL)grid[i][j]->moved=false;}//Loop through cells in order and move if it's a Doodlebugfor(i=0;i<WORLDSIZE;i++)for(j=0;j<WORLDSIZE;j++){if((grid[i][j]!=NULL)&&(grid[i][j]->getType()==DOODLEBUG)){if(grid[i][j]->moved==false){grid[i][j]->moved=true;//Mark as movedgrid[i][j]->move();}}}//Loop through cells in order and move if it's an Antfor(i=0;i<WORLDSIZE;i++)for(j=0;j<WORLDSIZE;j++){if((grid[i][j]!=NULL)&&(grid[i][j]->getType()==ANT)){if(grid[i][j]->moved==false){grid[i][j]->moved=true;//Mark as movedgrid[i][j]->move();}}}//Loop through cells in order and check if we should breedfor(i=0;i<WORLDSIZE;i++)for(j=0;j<WORLDSIZE;j++){//Kill off any doodlebugs that haven't eaten recentlyif((grid[i][j]!=NULL)&&(grid[i][j]->getType()==DOODLEBUG)){if(grid[i][j]->starve()){delete(grid[i][j]);grid[i][j]=NULL;}}}//Loop through cells in order and check if we should breedfor(i=0;i<WORLDSIZE;i++)for(j=0;j<WORLDSIZE;j++){//Only breed organisms that have moved,since//breeding places new organisms on the map we//don't want to try and breed thoseif((grid[i][j]!=NULL)&&(grid[i][j]->moved==true)){grid[i][j]->breed();}}}//======================//Organism Constructor//Sets a reference back to the World object.//======================Organism::Organism(){world=NULL;moved=false;breedTicks=0;x=0;y=0;}Organism::Organism(World*wrld,int x,int y){this->world=wrld;moved=false;breedTicks=0;this->x=x;this->y=y;wrld->setAt(x,y,this);}//======================//Organism destructor//No need to delete the world reference,//it will be destroyed elsewhere.//======================Organism::~Organism(){}//Start with the Ant classclass Ant:public Organism{friend class World;public:Ant();Ant(World*world,int x,int y);void breed();//Must define this since virtualvoid move();//Must define this since virtualint getType();//Must define this since virtualbool starve()//Return false,ant never starves{return false;}};//======================//Ant constructor//======================Ant::Ant():Organism(){}Ant::Ant(World*world,int x,int y):Organism(world,x,y) {}//======================//Ant Move//Look for an empty cell up,right,left,or down and//try to move there.//======================void Ant::move(){//Pick random direction to moveint dir=rand()%4;//Try to move up,if not at an edge and empty spotif(dir==0){if((y>0)&&(world->getAt(x,y-1)==NULL)){world->setAt(x,y-1,world->getAt(x,y));//Move to new spotworld->setAt(x,y,NULL);y--;}}//Try to move downelse if(dir==1){if((y<WORLDSIZE-1)&&(world->getAt(x,y+1)==NULL)){world->setAt(x,y+1,world->getAt(x,y));//Move to new spotworld->setAt(x,y,NULL);//Set current spot to emptyy++;}}//Try to move leftelse if(dir==2){if((x>0)&&(world->getAt(x-1,y)==NULL)){world->setAt(x-1,y,world->getAt(x,y));//Move to new spotworld->setAt(x,y,NULL);//Set current spot to emptyx--;}}//Try to move rightelse{if((x<WORLDSIZE-1)&&(world->getAt(x+1,y)==NULL)){world->setAt(x+1,y,world->getAt(x,y));//Move to new spotworld->setAt(x,y,NULL);//Set current spot to emptyx++;}}}//======================//Ant getType//This virtual function is used so we can determine//what type of organism we are dealing with.//======================int Ant::getType(){return ANT;}//======================//Ant breed//Increment the tick count for breeding.//If it equals our threshold,then clone this ant either//above,right,left,or below the current one.//======================void Ant::breed(){breedTicks++;if(breedTicks==ANTBREED){breedTicks=0;//Try to make a new ant either above,left,right,or downif((y>0)&&(world->getAt(x,y-1)==NULL)){Ant*newAnt=new Ant(world,x,y-1);}else if((y<WORLDSIZE-1)&&(world->getAt(x,y+1)==NULL)){Ant*newAnt=new Ant(world,x,y+1);}else if((x>0)&&(world->getAt(x-1,y)==NULL)){Ant*newAnt=new Ant(world,x-1,y);}else if((x<WORLDSIZE-1)&&(world->getAt(x+1,y)==NULL)){Ant*newAnt=new Ant(world,x+1,y);}}}//*****************************************************//Now define Doodlebug Class//*****************************************************class Doodlebug:public Organism{friend class World;public:Doodlebug();Doodlebug(World*world,int x,int y);void breed();//Must define this since virtualvoid move();//Must define this since virtualint getType();//Must define this since virtualbool starve();//Check if a doodlebug starves to deathprivate:int starveTicks;//Number of moves before starving};//======================//Doodlebug constructor//======================Doodlebug::Doodlebug():Organism(){starveTicks=0;}Doodlebug::Doodlebug(World*world,int x,int y):Organism(world,x,y) {starveTicks=0;}//======================//Doodlebug move//Look up,down,left or right for a bug.If one is found,move there //and eat it,resetting the starveTicks counter.//======================void Doodlebug::move(){//Look in each direction and if a bug is found move there//and eat it.if((y>0)&&(world->getAt(x,y-1)!=NULL)&&(world->getAt(x,y-1)->getType()==ANT)){delete(world->grid[x][y-1]);//Kill antworld->grid[x][y-1]=this;//Move to spotworld->setAt(x,y,NULL);starveTicks=0;//Reset hungery--;return;}else if((y<WORLDSIZE-1)&&(world->getAt(x,y+1)!=NULL)&&(world->getAt(x,y+1)->getType()==ANT)){delete(world->grid[x][y+1]);//Kill antworld->grid[x][y+1]=this;//Move to spotworld->setAt(x,y,NULL);starveTicks=0;//Reset hungery++;return;}else if((x>0)&&(world->getAt(x-1,y)!=NULL)&&(world->getAt(x-1,y)->getType()==ANT)){delete(world->grid[x-1][y]);//Kill antworld->grid[x-1][y]=this;//Move to spot。