类的继承

这里我只讲单继承

我信奉的原则是：越简单，越可靠

#include "stdafx.h"
#include "iostream.h"

class circle
{
private:
  int x,y;
public:
  int r;//以便被继承
  circle(int a,int b,int c);
  void print();
};

circle::circle(int a,int b,int c)
{
        x=a;
  y=b;
  r=c;
}
void circle::print()
{
  cout<< "圆心：("<<x<< ","<<y<< ")"<<endl;
  cout<< "半径："<<r<<endl;
}

class cylinder: public circle
{
private:
  int h;
public:
  cylinder(int a,int b,int c,int d);
  void print();
  void volume();
};

cylinder::cylinder(int a,int b,int c,int d):circle(a,b,c)//继承
{
  h=d;
}
void cylinder::print()
{
  circle::print();
  cout<< "高为："<<h<<endl;
}
void cylinder::volume()
{
  cout<< "圆柱体体积为："<<3.14*r*r*h<<endl;//由于继承下来了一个r，这个r就当作本身的同样 } int main() {   cylinder p(0,0,1,3);   p.print();   p.volume();   return 0; }