//建立一个栈类，能够存放图形元素（矩形或圆形），有入栈，出栈。

　　//取栈顶的功能。建立元素类，里面至少一个纯虚函数，矩形和圆形类。

　　//来实现里面的函数SHOWME，实现他的显示图形信息的功能。重载>>.

　　//能够输入图形信息。测试以上类的功能。

#include "stdafx.h"
#include "iostream.h"
#include "string.h"
const n=50;
class shape
{
protected:
 double width, length;
public:
 shape() {}
 virtual void ShowMe()=0;
};
class rectangle:public shape
{
public:
 rectangle():shape(){}
 friend istream &operator>>(istream &is, rectangle &rec)
 {
 cout<<"请输入长方形的长：";
 is>>rec.length;
 cout<<"请输入长方形的宽：";
 is>>rec.width;
 return is;
 }
 void ShowMe()
 {
 cout<<"长方形的长宽分别为：("<<length
 <<","<<width<<")"<<endl; 
 }
};
class circle:public shape
{
private:
 //double x, y;
 double r;
public:
 circle():shape()
 friend istream &operator>>(istream &is, circle &cir)
 {
 cout<<"请输入圆的圆心坐标(x,y)：";
 is>>cir.width;
 is>>cir.length;
 cout<<"请输入圆的半径：";
 is>>cir.r;
 return is;
 }
 void ShowMe()
 {
 cout<<"圆的圆心坐标为：("<<width<<","<<length<<")"
 <<" 半径为："<<r<<endl;
 }
};
class stack
{
 shape *sp[n];
 rectangle rec[n];
 circle cir[n];
 int size;
public:
 stack()
 {
 for (int i=0; i<n; i++)
 sp[i]=NULL;
 size=-1;
 }
 bool empty(){return size==-1;}
 bool full(){return size==n-1;}
 void push(rectangle &rect)
 {
 rec[++size]=rect;
 sp[size]=new rectangle;
 sp[size]=&rec[size];
 }
 void push(circle &circ)
 {
 cir[++size]=circ;
 sp[size]=new circle;
 sp[size]=&cir[size];
 }
 void top()
 {
 if (empty()) cout<<"栈为空"<<endl;
 else {
 cout<<"栈顶元素为:"<<endl;
 sp[size]->ShowMe(); 
 }
 
 }
 void pop()
 {
 if (empty()) cout<<"栈为空"<<endl;
 else {
 cout<<"出栈元素为:"<<endl;
 sp[size--]->ShowMe(); 
 }
 }
};
void main()
{
 stack Stack;
 rectangle rec;
 circle cir;
 int s=1;
 while (s)
 {
 cout<<endl;
 cout<<"请选择1-5号键*作"<<endl;
 cout<<" 1: 矩形进栈;"<<endl;
 cout<<" 2: 圆进栈;"<<endl;
 cout<<" 3: 显示栈顶元素;"<<endl;
 cout<<" 4: 出栈;"<<endl;
 cout<<" 5: 退出程序;"<<endl;
 cin>>s;
 switch(s)
 {
 case 1: cin>>rec; Stack.push(rec); break;
 case 2: cin>>cir; Stack.push(cir); break;
 case 3: Stack.top(); break;
 case 4: Stack.pop(); break;
 case 5: s=0; break;
 //default: cout<<"请重新输入"<<endl; break;
 }
 }
}