这个类这样写为什么会有问题
这个类这样写为什么会有问题,正确的要怎么写
#include<iostream>
using namespace std;
class rectangle
{private:
double chang;
double kuan;
public:
rectangle(double x,double y)
{
chang=x;
kuan=y;
}
double zhouchang()
{
double z;
z=(chang+kuan)*2;
return z;
}
double mianji()
{
double z;
z=chang*kuan;
return z;
}
};
class zheng:public rectangle
{
public:
/*void panduan()
{if(chang==kuan)
cout<<"是正方形"<<endl;
else
cout<<"不是正方形"<<endl;
}*/
void jisuan()
{
cout<<zhouchang()<<endl<<mianji()<<endl;
}
};
int main()
{
rectangle a1(5,5);
zheng a2;
a2.jisuan();
return 0;
}