使用虛析構(gòu)函數(shù)谓着，才能調(diào)用子類的析構(gòu)函數(shù)
virtual在函數(shù)中的使用限制
1.普通函數(shù)不能是虛函數(shù)
2.靜態(tài)成員不能是虛函數(shù)
3.內(nèi)聯(lián)函數(shù)不能是虛函數(shù)
4.構(gòu)造函數(shù)不能為虛函數(shù)
Shape.h
#ifndef SHAPE_H
#define SHAPE_H
#include <iostream>
using namespace std;
class Shape {
public:
Shape();
~Shape();
virtual double calcArea();
};
#endif
Shape.cpp
#include "Shape.h"
Shape::Shape()
{
cout << "Shape()" << endl;
}
Shape::~Shape() {
cout << "~Shape()" << endl;
}
double Shape::calcArea()
{
cout << "Shape->calcArea()" << endl;
return 0;
}
Coordinate.h
#ifndef COORDINATE_H
#define COORDINATE_H
class Coordinate {
public:
Coordinate(int x,int y);
~Coordinate();
private:
int m_iX;
int m_iY;
};
#endif
Coordinate.cpp:
#include"Coordinate.h"
#include <iostream>
using namespace std;
Coordinate::Coordinate(int x, int y)
{
cout << "Coordinate" << endl;
m_iX = x;
m_iY = y;
}
Coordinate::~Coordinate()
{
cout << "~Coordinate()" << endl;
}
Circle.h
#ifndef CIRCLE_H
#define CIRCLE_H
#include "Shape.h"
#include "Coordinate.h"
class Circle : public Shape{
public:
Circle(double r);
~Circle();
double calcArea();
protected:
double m_dR;
Coordinate *m_pCenter;
};
#endif
Circle.cpp:
#include "Circle.h"
Circle::Circle(double r)
{
cout << "Circle()" << endl;
m_dR = r;
m_pCenter = new Coordinate(3, 5);
}
Circle::~Circle()
{
cout << "~Circle()" << endl;
delete m_pCenter;
m_pCenter = NULL;
}
double Circle::calcArea() {
cout << "Ciecle->calcArea()" << endl;
return 3.14*m_dR*m_dR;
}
demo.cpp:
#include "Circle.h"
int main(void)
{
Shape *shape2 = new Circle(5);
delete shape2;
system("pause");
return 0;
}
運行
Paste_Image.png
修改
#ifndef SHAPE_H
#define SHAPE_H
#include <iostream>
using namespace std;
class Shape {
public:
Shape();
virtual~Shape();
virtual double calcArea();
};
#endif
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