Читаем C++ Primer Plus полностью

C++ Primer Plus

Стивен Прата

Cd(char * s1, char * s2, int n, double x);

Cd(const Cd & d);

Cd();

~Cd();

void Report() const; // reports all CD data

Cd & operator=(const Cd & d);

};

Derive a Classic class that adds an array of char members that will hold a string identifying the primary work on the CD. If the base class requires that any functions be virtual, modify the base-class declaration to make it so. If a declared method is not needed, remove it from the definition. Test your product with the following program:

#include

using namespace std;

#include "classic.h" // which will contain #include cd.h

void Bravo(const Cd & disk);

int main()

{

Cd c1("Beatles", "Capitol", 14, 35.5);

Classic c2 = Classic("Piano Sonata in B flat, Fantasia in C",

"Alfred Brendel", "Philips", 2, 57.17);

Cd *pcd = &c1

cout << "Using object directly:\n";

c1.Report(); // use Cd method

c2.Report(); // use Classic method

cout << "Using type cd * pointer to objects:\n";

pcd->Report(); // use Cd method for cd object

pcd = &c2

pcd->Report(); // use Classic method for classic object

cout << "Calling a function with a Cd reference argument:\n";

Bravo(c1);

Bravo(c2);

cout << "Testing assignment: ";

Classic copy;

copy = c2;

copy.Report()

return 0;

}

void Bravo(const Cd & disk)

{

disk.Report();

}

2. Do Programming Exercise 1 but use dynamic memory allocation instead of fixed-size arrays for the various strings tracked by the two classes.

3. Revise the baseDMA-lacksDMA-hasDMA class hierarchy so that all three classes are derived from an ABC. Test the result with a program similar to the one in Listing 13.10. That is, it should feature an array of pointers to the ABC and allow the user to make runtime decisions as to what types of objects are created. Add virtual View() methods to the class definitions to handle displaying the data.

4. The Benevolent Order of Programmers maintains a collection of bottled port. To describe it, the BOP Portmaster has devised a Port class, as declared here:

#include

using namespace std;

class Port

{

private:

char * brand;

char style[20]; // i.e., tawny, ruby, vintage

int bottles;

public:

Port(const char * br = "none", const char * st = "none", int b = 0);

Port(const Port & p); // copy constructor

virtual ~Port() { delete [] brand; }

Port & operator=(const Port & p);

Port & operator+=(int b); // adds b to bottles

Port & operator-=(int b); // subtracts b from bottles, if available

int BottleCount() const { return bottles; }

virtual void Show() const;

friend ostream & operator<<(ostream & os, const Port & p);

};

The Show() method presents information in the following format:

Brand: Gallo

Kind: tawny

Bottles: 20

The operator<<() function presents information in the following format (with no newline character at the end):

Gallo, tawny, 20

The Portmaster completed the method definitions for the Port class and then derived the VintagePort class as follows before being relieved of his position for accidentally routing a bottle of ‘45 Cockburn to someone preparing an experimental barbecue sauce:

class VintagePort : public Port // style necessarily = "vintage"

{

private:

char * nickname; // i.e., "The Noble" or "Old Velvet", etc.

int year; // vintage year

public:

VintagePort();

VintagePort(const char * br, int b, const char * nn, int y);

VintagePort(const VintagePort & vp);

~VintagePort() { delete [] nickname; }

VintagePort & operator=(const VintagePort & vp);

void Show() const;