Ｃ++高级程序设计-第12章 继承和派生(例子).docVIP

例12.1 先定义“点”类Point， 再由“点”类派生出“圆”类Circle。 #include iostream.h #define PI 3.14159 class Point // 定义“点”类 { int x, y; public: Point(int a=0, int b=0) { x=a; y=b; } void ShowPoint( ) { coutPoint:(x,y)\n; } int Getx( ) { return x; } int Gety( ) { return y; } void Setxy(int a, int b) { x=a; y=b; } }; class Circle: public Point // 定义“圆”类，公有继承 { int r; // “圆”的半径 public: Circle(int x, int y, int ra) : Point(x, y) // B { r = ra; } void Setr(int ra) { r = ra; } double Area( ) //求圆的面积 { return PI*r*r; } void Move(int x_offset, int y_offset) //将圆心坐标平移 { int x1=Getx( ); //存取基类的私有成员 int y1=Gety( ); // D x1 += x_offset; y1 += y_offset; Setxy(x1, y1); // E } void ShowCircle( ) { ShowPoint( ); // F cout Radius: r\t; coutArea: Area( )endl; //G } }; void main( ) { Circle c(1, 1, 1); c.ShowCircle( ); c.Move(1, 2); c.ShowCircle( ); c.Setxy(4, 5); //重新置圆心坐标 c.Setr(2); //重新置半径值 c.ShowCircle( ); } 回ppt讲稿 例12.2 先定义“点”类Point和“半径”类Radius，再由Point类和Radius类多重派生出“圆”类Circle。 #include iostream.h #define PI 3.14159 class Point { protected: //A int x, y; public: Point(int a=0, int b=0){ x=a; y=b; } void ShowPoint( ) { coutPoint:(x,y)\n;} int Getx( ) { return x; } int Gety( ) { return y; } void Setxy(int a, int b){ x=a; y=b; } }; class Radius { protected: //B int r; public: Radius(int ra=0){ r = ra; } void Setr(int ra){ r = ra; } int Getr( ) { return r; } }; class Circle : public Point, public Radius { public: Circle(int x, int y, int ra) : Point(x, y), Radius(ra) //D { } double Area( ) { return PI*r*r; } //直接访问基类的保护成员 void Move(int x_offset, int y_offset) { x += x_offset; y += y_offset; } void ShowCircle( ) { ShowPoint( ); coutRadius: r\t; coutArea: Area( )endl; } }; void main( ) { Circle c(1, 1, 1); c.ShowCircle( ); c.Move(1, 2); c.ShowCircle( ); c.Setxy(4