#include<iostream>
#include<string>
using namespace std;
class A
{ double a,b;
public:
    A(double i,double j)
    {i=a;j=b;}
    double S()
    {return a*b;}
    double L()
    {return Z*(a+b);}
    class B:public A
    {
        double h;
    public:B(double i,double j,double k)
           {h=k;}
           double V()
           {return S()*h;}
           double S1()
           {return L()*h+2*S();}
    }
    void main()
    { B b1(2,4.2,5.1)
    cout<<"S="<<b1.S()<<end1;
    cout<<"S1="<<b1.s1()<<end1;
    }

额，你应该去看下类的定义。。

#include<iostream>

using namespace std;

class A
{
    double a,b;
public:
    A(double i,double j)
    {i=a;j=b;}
    double S()
    {return a*b;}
    double L()
    {return 2*(a+b);}
};

 class B:public A
    {
        double h;

    public:B(double i,double j,double k) :A(i,j)
           {h=k;}
           double V()
           {return S()*h;}
           double S1()
           {return L()*h+2*S();}
    };

    int  main()
    { B b1(2,4.2,5.1);
    cout<<"S="<<b1.S()<<endl;
    cout<<"S1="<<b1.S1()<<endl;

    return 0;
    }