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Polymorphism
Problem - Item Class
Problem description.
Item class
% cat item.h
#ifndef ITEM_H
#define ITEM_H
class Item
{
protected:
string title;
double price;
int invent;
public:
Item();
Item(string t, double p, int i);
int getInvent() const;
void setInvent(int i);
virtual void
invoice(ostream &out) const;
};
#endif
% cat item.cpp
#include<iostream>
using namespace std;
#include<fstream>
#include "item.h"
Item::Item() : title("item"), price(0.0), invent(0) {}
Item::Item(string t, double p, int i): title(t), price(p),
invent(i) {}
int Item::getInvent() const
{
return invent;
}
void Item::setInvent(int i)
{
invent = i;
}
void Item::invoice(ostream & out) const
{
out.setf(ios::fixed | ios::showpoint);
out.precision(2);
out << "Item = " << title << "\nPrice = $"
<< price << endl;
}
Book class
% cat book.h
#ifndef BOOK_H
#define BOOK_H
class Book : public Item
{
protected:
string author;
int year;
public:
Book();
Book(string t, double p, int i, string a, int y);
void invoice( ostream &out ) const;
};
#endif
% cat book.cpp
#include<iostream>
using namespace std;
#include "item.h"
#include "book.h"
Book::Book() : Item(), author("author"), year(1900) {}
Book:: Book(string t, double p, int i, string a, int y) :
Item(t, p, i), author(a), year(y) {}
void Book::invoice( ostream &out) const
{
out.setf(ios::fixed | ios::showpoint);
out.precision(2);
out << "Book: " << title
<< "\nAuthor: " << author
<< "\nPublished: " << year
<< "\nPrice = $" << price
<< endl;
}
Candle class
% cat candle.h
#ifndef CANDLE_H
#define CANDLE_H
class Candle : public Item
{
protected:
string color;
int size;
public:
Candle();
Candle(string t, double p, int i, string a, int y);
void invoice( ostream &out ) const;
};
#endif
% cat candle.cpp
#include<iostream>
using namespace std;
#include "item.h"
#include "candle.h"
Candle::Candle() : Item(), color("color"), size(1) {}
Candle:: Candle(string t, double p, int i, string c, int s) :
Item(t, p, i), color(c), size(s) {}
void Candle::invoice( ostream &out) const
{
out.setf(ios::fixed | ios::showpoint);
out.precision(2);
out << "Candle: " << title
<< "\nColor: " << color
<< "\nDiameter: " << size
<< " inches"
<< "\nPrice = $" << price
<< endl;
}
Card class
% cat card.h
#ifndef CARD_H
#define CARD_H
class Card : public Item
{
protected:
string event;
public:
Card();
Card(string t, double p, int i, string e);
void invoice( ostream &out ) const;
};
#endif
% cat card.cpp
#include<iostream>
using namespace std;
#include "item.h"
#include "card.h"
Card::Card() : Item(), event("event") {}
Card:: Card(string t, double p, int i, string e) :
Item(t, p, i), event(e) {}
void Card::invoice( ostream &out) const
{
out.setf(ios::fixed | ios::showpoint);
out.precision(2);
out << "Card: " << title
<< "\nEvent: " << event
<< "\nPrice = $" << price
<< endl;
}
Driver program
% cat item_test.cpp
#include<iostream>
using namespace std;
#include<fstream>
#include "item.h"
#include "book.h"
#include "candle.h"
#include "card.h"
int main()
{
Book text;
text.invoice( cout );
cout << "\nNumber in inventory = " <<
text.getInvent() << endl;
cout << endl;
Book C_text("Advanced C++", 125.50, 42, "John B. Good", 2008);
C_text.invoice( cout );
cout << "\nNumber in inventory = " <<
C_text.getInvent() << endl
<< endl;
// Candle class
Candle cand;
cand.invoice( cout );
cout << endl;
Candle holiday("Holiday", 12.95, 50, "red", 3);
holiday.invoice(cout);
cout << endl;
// Card class
Card crd;
crd.invoice( cout );
cout << endl;
Card ghd("Box of 25", 18.50, 85, "Ground Hog Day");
ghd.invoice(cout);
cout << "\nPolymorphism\n\n";
// polymorphism
Item *base_pointer;
base_pointer =
&C_text; // point to a Book object
(*base_pointer).invoice(cout);
cout << endl;
base_pointer =
&holiday; // point to a Candle object
(*base_pointer).invoice(cout);
return 0;
}
Compile & execute
% g++ item_test.cpp item.cpp book.cpp candle.cpp card.cpp
% a.out
Book: item
Author: author
Published: 1900
Price = $0.00
Number in inventory = 0
Book: Advanced C++
Author: John B. Good
Published: 2008
Price = $125.50
Number in inventory = 42
Candle: item
Color: color
Diameter: 1 inches
Price = $0.00
Candle: Holiday
Color: red
Diameter: 3 inches
Price = $12.95
Card: item
Event: event
Price = $0.00
Card: Box of 25
Event: Ground Hog Day
Price = $18.50
Polymorphism
Book: Advanced C++
Author: John B. Good
Published: 2008
Price = $125.50
Candle: Holiday
Color: red
Diameter: 3 inches
Price = $12.95
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