Question

求一个50行以上的C++程序，要求含有三个以上的类，且含有基类和派生类

Answer 1

一个基类，两个派生类
/***********************************************
*4-2
************************************************/

#include <iostream.h>
#define PI 3.1415926

//抽象基类
class Shape
{
public:
Shape(float x,float y)
{
m_length=x;
m_width=y;
}

virtual const float GetArea(){return 0.0;}
virtual const float GetPerim()=0;
protected:
float m_length;//长
float m_width;//宽
};
//end

//矩形类
class Rectangle:public Shape
{
public:
Rectangle(float x,float y):Shape(x,y){}

const float GetArea()
{
return m_length*m_width;
}

const float GetPerim()
{
return 2*(m_length+m_width);
}
};
//end

//圆类
class Circle:public Shape
{
public:
Circle(float r,float x=0,float y=0):Shape(x,y)
{
m_radius=r;
}

const float GetArea()
{
return PI*m_radius*m_radius;
}

const float GetPerim()
{
return 2*PI*m_radius;
}
protected:
float m_radius;//半径
};
//end

int main(void)
{
Rectangle rect(10,6);
Circle fat(5);
Shape *p;
p=▭
cout<<p->GetArea()<<endl;
cout<<p->GetPerim()<<endl;
p=&fat;
cout<<p->GetArea()<<endl;
cout<<p->GetPerim()<<endl;
return 0;
}

Answer 2

#include <iostream.h>
class Base{
public:
Base() { cout << "Constructing Base… \n"; }
virtual void myname() { cout << " Base \n"; }
};
class Point: public Base{
public:
Point() { cout << "Constructing Point...\n"; }
void myname() { cout << "Point \n"; }
};
class Circle: public Point{
public:
virtual void myname() { cout << "Circle \n"; }
};
class Cylinder: public Circle{ };
Base o1; Cylinder o2;
int main( )
{ Base a; Point b; Circle c; Cylinder d;
Base * pv[4]={&a,&b,&c,&d};
Base v[4]={a,b,c,d};
for (int i=0;i<4;i++)
{ pv[i]->myname();
v[i]. myname();
}
return 0;
}

Answer 3

哎，来晚了。