C++笔记(5)：继承和多态代码实现

Shape.h

 1 #ifndef SHAPE_H
 2 #define SHAPE_H
 3 #include<string>
 4 using std::string;
 5
 6 class IShape
 7 {
 8 public:
 9     virtual float getArea()=0;
10     virtual string getName()=0;
11 };
12
13 #endif

Circle.h

 1 #ifndef CIRCLE_H
 2 #define CIRCLE_H
 3 #include"Shape.h"
 4 class CCircle : public IShape
 5 {
 6 public:
 7     CCircle(float radius);
 8 public:
 9     virtual float getArea();
10     virtual string getName();
11
12 private:
13     float m_fRadius;
14 };
15
16 #endif

Circle.cpp

 1 #include"Circle.h"
 2
 3 CCircle::CCircle(float radius)
 4     :m_fRadius(radius)     //冒号表示初始化列表，m_fRadius表示变量名，radius表示变量初始值大小，注意不是继承符号
 5 {
 6 }
 7
 8 float CCircle::getArea()
 9 {
10     return 3.14 * m_fRadius * m_fRadius;
11 }
12
13 string CCircle::getName()
14 {
15     return "CCircle";
16 }

Rect.h

 1 #ifndef RECT_H
 2 #define RECT_H
 3 #include"shape.h"
 4 class CRect : public IShape
 5 {
 6 public:
 7     CRect(float nWidth, float nHeight);
 8
 9 public:
10     virtual float getArea();
11     virtual string getName();
12
13 private:
14     float  m_fWidth;
15     float  m_fHeight;
16 };
17
18
19 #endif

Rect.cpp

 1 #include"Rect.h"
 2
 3 CRect::CRect(float fWidth, float fHeight)
 4     :m_fWidth(fWidth), m_fHeight(fHeight)       //冒号同样表示初始化列表，不是继承符号，注意区分
 5 {
 6 }
 7
 8 float CRect::getArea()
 9 {
10     return m_fWidth * m_fHeight;
11 }
12
13 string CRect::getName()
14 {
15     return "CRect";
16 }

main.cpp

 1 #include<iostream>
 2 #include"Rect.h"
 3 #include"Circle.h"
 4 using namespace std;
 5
 6 int main()
 7 {
 8     IShape* pShape = NULL;
 9     pShape = new CCircle(20.2);         //基类的指针pShape指向派生类对象circle
10     cout<<pShape->getName()<<" "<<pShape->getArea()<<endl;
11
12     delete pShape;
13     pShape = new CRect(20, 10);　　　　 //基类的指针pShape指向派生类对象crect

14 　　cout<<pShape->getName()<<" "<<pShape->getArea()<<endl; 15 16 　　return 0; 17 }