// Fig. 10.13: shape.cpp
// Shape class member-function definitions.
#include <iostream>
using std::cout;
#include "shape.h" // Shape class definition
// return area of shape; 0.0 by default
double Shape::getArea() const
{
return 0.0;
} // end function getArea
// return volume of shape; 0.0 by default
double Shape::getVolume() const
{
return 0.0;
}
[code/]
------------------------------------------------------------------
اینم یکی از کلاسهایی که ازش به ارث میبره:
[code]
#ifndef POINT_H
#define POINT_H
#include "shape.h" // Shape class definition
class Point : public Shape {
public:
Point( int = 0, int = 0 ); // default constructor
void setX( int ); // set x in coordinate pair
int getX() const; // return x from coordinate pair
void setY( int ); // set y in coordinate pair
int getY() const; // return y from coordinate pair
// return name of shape (i.e., "Point" )
virtual string getName() const;
virtual void print() const; // output Point object
private:
int x; // x part of coordinate pair
int y; // y part of coordinate pair
}; // end class Point
#endif
[code/]
---------------------------------------------------------
پیاده سازی :
[code]
#include <iostream>
using std::cout;
#include "point.h" // Point class definition
// default constructor
Point::Point( int xValue, int yValue )
: x( xValue ), y( yValue )
{
// empty body
} // end Point constructor
// set x in coordinate pair
void Point::setX( int xValue )
{
x = xValue; // no need for validation
} // end function setX
// return x from coordinate pair
int Point::getX() const
{
return x;
} // end function getX
// set y in coordinate pair
void Point::setY( int yValue )
{
y = yValue; // no need for validation
} // end function setY
// return y from coordinate pair
int Point::getY() const
{
return y;
} // end function getY
// override pure virtual function getName: return name of Point
string Point::getName() const
{
return "Point";
} // end function getName
// override pure virtual function print: output Point object
void Point::print() const
{
cout << '[' << getX() << ", " << getY() << ']';
} // end function print
[code/]
---------------------------------------------------------
2 تا کلاس دیگه هم ازش به ارث میبرن:
[code]
#ifndef CIRCLE_H
#define CIRCLE_H
#include "point.h" // Point class definition
class Circle : public Point {
public:
// default constructor
Circle( int = 0, int = 0, double = 0.0 );
void setRadius( double ); // set radius
double getRadius() const; // return radius
double getDiameter() const; // return diameter
double getCircumference() const; // return circumference
virtual double getArea() const; // return area
// return name of shape (i.e., "Circle")
virtual string getName() const;
virtual void print() const; // output Circle object
private:
double radius; // Circle's radius
}; // end class Circle
#endif
[code/]
-----------------------------------------------------------
پیاده سازی:
[code]
#include <iostream>
using std::cout;
#include "circle.h" // Circle class definition
// default constructor
Circle::Circle( int xValue, int yValue, double radiusValue )
: Point( xValue, yValue ) // call base-class constructor
{
setRadius( radiusValue );
} // end Circle constructor
// set radius
void Circle::setRadius( double radiusValue )
{
radius = ( radiusValue < 0.0 ? 0.0 : radiusValue );
} // end function setRadius
// return radius
double Circle::getRadius() const
{
return radius;
} // end function getRadius
// calculate and return diameter
double Circle::getDiameter() const
{
return 2 * getRadius();
} // end function getDiameter
// calculate and return circumference
double Circle::getCircumference() const
{
return 3.14159 * getDiameter();
} // end function getCircumference
// override virtual function getArea: return area of Circle
double Circle::getArea() const
{
return 3.14159 * getRadius() * getRadius();
} // end function getArea
// override virutual function getName: return name of Circle
string Circle::getName() const
{
return "Circle";
} // end function getName
// override virtual function print: output Circle object
void Circle::print() const
{
cout << "center is ";
Point::print(); // invoke Point's print function
cout << "; radius is " << getRadius();
} // end function print
[code/]
----------------------------------------------------------------
اون یکی کلاس دیگه تقریبا مثل همینه.
این هم تابع اصلی:
[code]
#include <iostream>
using std::cout;
using std::endl;
using std::fixed;
#include <iomanip>
using std::setprecision;
#include <vector>
using std::vector;
#include "shape.h" // Shape class definition
#include "point.h" // Point class definition
#include "circle.h" // Circle class definition
#include "cylinder.h" // Cylinder class definition
void virtualViaPointer( const Shape * );
void virtualViaReference( const Shape & );
int main()
{
// set floating-point number format
cout << fixed << setprecision( 2 );
Point point( 7, 11 ); // create a Point
Circle circle( 22, 8, 3.5 ); // create a Circle
Cylinder cylinder( 10, 10, 3.3, 10 ); // create a Cylinder
cout << point.getName() << ": "; // static binding
point.print(); // static binding
cout << '\n';
cout << circle.getName() << ": "; // static binding
circle.print(); // static binding
cout << '\n';
cout << cylinder.getName() << ": "; // static binding
cylinder.print(); // static binding
cout << "\n\n";
// create vector of three base-class pointers
vector< Shape * > shapeVector( 3 );
// aim shapeVector[0] at derived-class Point object
shapeVector[ 0 ] = &point;
// aim shapeVector[1] at derived-class Circle object
shapeVector[ 1 ] = &circle;
// aim shapeVector[2] at derived-class Cylinder object
shapeVector[ 2 ] = &cylinder;
// loop through shapeVector and call virtualViaPointer
// to print the shape name, attributes, area and volume
// of each object using dynamic binding
cout << "\nVirtual function calls made off "
<< "base-class pointers:\n\n";
for ( int i = 0; i < shapeVector.size(); i++ )
virtualViaPointer( shapeVector[ i ] );
// loop through shapeVector and call virtualViaReference
// to print the shape name, attributes, area and volume
// of each object using dynamic binding
cout << "\nVirtual function calls made off "
<< "base-class references:\n\n";
for ( int j = 0; j < shapeVector.size(); j++ )
virtualViaReference( *shapeVector[ j ] );
return 0;
} // end main
// make virtual function calls off a base-class pointer
// using dynamic binding
void virtualViaPointer( const Shape *baseClassPtr )
{
cout << baseClassPtr->getName() << ": ";
baseClassPtr->print();
cout << "\narea is " << baseClassPtr->getArea()
<< "\nvolume is " << baseClassPtr->getVolume()
<< "\n\n";
} // end function virtualViaPointer
// make virtual function calls off a base-class reference
// using dynamic binding
void virtualViaReference( const Shape &baseClassRef )
{
cout << baseClassRef.getName() << ": ";
baseClassRef.print();
cout << "\narea is " << baseClassRef.getArea()
<< "\nvolume is " << baseClassRef.getVolume() << "\n\n";
} // end function virtualViaReference
[code/]
---------------------------------------------
البته کلاس cylinder رو ننوشتم چون مشابه circle هست فقط یه تابع اضافه برای محاسبه حجم داره.اگه نیازی بود بگید.ممنون از توجهتون
rint(void)const " (?print@Cyliner@@UBEXXZ)
