A Complete Guide to Programming in C++ part 63 pps

In addition to access methods, also define the method display, which outputs the data members of an apartment.. ■ Define a class derived from the CarandHomeclasses called MotorHome, whic

Exercise 1

The multiply-derived class MotorHomeneeds to be fully implemented and tested.

■ Define an enumeration type CATEGORYthat represents the categories

“Luxury,” “First Class,” “Middle Class,” and “Economy”.

■ Develop a class called Homewith two data members used to store the number of rooms and the size in square meters Supply default values for your constructor definition to create a default constructor In addition to access methods, also define the method display(), which outputs the data members of an apartment.

■ Define a class derived from the CarandHomeclasses called MotorHome, which is used to represent motorhomes Inheritance of publicbase classes is used.The MotorHomeclass contains a new data member used to store one value of the CATEGORYtype In addition to defining a construc-tor with default values, also define appropriate access methods and a display()method for output.

Place your definitions of the HomeandMotorHomeclasses in a separate header file, which includes the existing header file car.h.

■ Write a mainfunction that first fully initializes a MotorHometype object and then outputs the object.

Then create a second instance of the MotorHometype without initial val-ues and display the object on screen Call all the set methods in the MotorHomeclass and its base classes to set your own values for the objects.Then output the object once more.

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Class hierarchy for the multiply-derived class SUV

Car

Data members:

car number producer

SUV

Data members:

number of seats

PassCar

Data members:

car type sun roof (y/n)

Van

Data members: capacity (lbs)

Exercise 2

Now fully define the SUVclass for testing virtual base classes.

■ Change the definition of the PassCarclass in the car.hheader file to make Cara virtual base class of the PassCarclass.

■ Then define the Vanclass using the Carclass as a virtual base class.The new class should contain an additional data member used to represent the payload of the van in kilograms.A maximum of 750 kg applies to vans The constructor should use default values to initialize the data members with defaults, thus providing a default constructor for the class.A maxi-mum value of 750 applies for the payload In addition to the access

methoddisplay(), you still need to define methods for screen output.

■ Create the class SUV, which is derived from PassCarandVan, to repre-sent a station wagon Store the number of seats available in the station wagon as a data member.

The constructor in the SUVclass should use the base initializer to set all the values of a station wagon using default values for every data member Additionally, define access methods and a display()to define output.

■ Use a mainfunction to test the SUVclass; the function should create sta-tion wagons with and without default values and display them on screen.

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■ SOLUTIONS

Exercise 1

// -// car.h : Definition of base class Car and

// derived classes PassCar and Truck // -// car.cpp

// Implementing methods of Car, PassCar, and Truck // -//

// These files have been left unchanged // from Chapters 23 and 25

//

// -// motorHome.h : Definition of the class Home and the // multiply-derived class MotorHome //

-#ifndef _MOTORHOME_H_

#define _MOTORHOME_H_

#include "car.h"

#include <iomanip>

#include <iostream>

using namespace std;

enum CATEGORY {LUXURY, FIRSTCLASS, SECONDCLASS, ECONOMY};

class Home

{ private:

int room;

double ft2;

public:

Home(int r = 0, double m2 = 0.0) { room = r; ft2 = m2;}

void setRoom(int n){ room = n;}

int getRoom() const { return room; } void setSquareFeet(double m2){ ft2 = m2;}

double getSquareFeet() const { return ft2; } void display() const

{ cout << "Number of rooms: " << room

<< "\nSquare feet: "

<< fixed << setprecision(2) << ft2 << endl; }

};

class MotorHome : public Car, public Home

{

private:

CATEGORY cat;

public:

MotorHome(long n=0L, const string& prod="", int ro=0,

double m2=0.0, CATEGORY k=ECONOMY) : Car(n, prod), Home(ro, m2), cat(k)

{}

void setCategory(CATEGORY c){cat = c;}

CATEGORY getCategory() const { return cat;}

void display() const

{

cout << "\nMotorHome: ";

Car::display();

Home::display();

cout << "Category: ";

switch(cat)

{

case LUXURY: cout << " Luxury";

break;

case FIRSTCLASS: cout << " First class";

break;

case SECONDCLASS: cout << " Second class";

break;

case ECONOMY: cout << " Economy";

break;

}

cout << endl;

}

};

#endif

//

-// motorHome_t.cpp

// Testing the multiply-derived class MotorHome

//

-#include "motorHome.h"

int main()

{

MotorHome rv(12345L, "Texaco", 2, 40.5, LUXURY);

rv.display();

MotorHome holiday;

holiday.display(); // Default values

cin.get();

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holiday.setNr(54321);

holiday.setProd("VW");

holiday.setRoom(1);

holiday.setSquareFeet(11.5);

holiday.setCategory(SECONDCLASS);

holiday.display();

return 0;

}

Exercise 2

// -// car.h : Definition of base class Car and

// the derived classes PassCar and Truck // -// car.cpp

// Implementing the methods of Car, PassCar, and Truck // -//

// These files are carried over from Chapter 23 and 25, // with the following changes:

//

// Class Car is a virtual base class now class PassCar : public virtual Car

{ //

};

class Truck : public virtual Car

{ //

};

// -// suv.h : Defines the class Van and

// the multiply-derived class SUV //

-#ifndef _SUV_H

#define _SUV_H

#include "car.h"

class Van : public virtual Car

{ private:

double capacity;

Van(long n=0L, const string& prod="",

double l=0.0) : Car(n,prod)

{

if(l > 750) l = 750;

capacity = l;

}

void setCapacity(double l)

{

if(l > 750)

capacity= 750;

else

capacity = l;

}

double getCapacity() const { return capacity; }

void display() const

{

cout << "Capacity: "

<< capacity << " kg" << endl;

}

};

class SUV : public PassCar, public Van

{

private:

int cnt; // Number of seats

public:

SUV(const string& tp="without type", bool sb=false,

long n=0L, const string& prod=" none ",

double l=0.0, int z = 1)

: PassCar(tp,sb), Car(n,prod),

Van(n,prod,l), cnt(z)

{ }

void display() const

{

PassCar::display();

Van::display();

cout << "Number of seats: " << cnt << endl;

}

};

#endif

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// -// suv_t.cpp : Tests the class SUV

//

-#include "suv.h"

int main() {

SUV mobil("Bravada", true, 120345, "Oldsmobile",350,6); mobil.display();

SUV trucky;

trucky.display();

trucky.setNr(543221);

trucky.setProd("Renault");

trucky.setCapacity(1000.);

trucky.display();

return 0;

}

6 0 7

Exception Handling

This chapter describes how a C++ program uses error-handling

techniques to resolve error conditions In addition to throwing and catching exceptions, we also examine how exception specifications are declared and exception classes are defined, additionally looking into the use of standard exception classes.

chapter 28

608 C H A P T E R 2 8 E X C E P T I O N H A N D L I N G

■ TRADITIONAL ERROR HANDLING

Error checking after leaving a function

First calling function

Second calling function

Third calling function

Called function

{ if(func()>0) // every-// thing // is ok else exit(-1);

}

{ if(func()<=0) // All errors // are

// handled

}

{ x= func(); if(x == 0) //1 error else if (x == -1) //2 error }

int func( void) {

if(dilemma) return 0;

if(catastrophe) return -1;

}