求助 错在那边

C/C++ code

#include <iostream>using namespace std;class b{public:    b(){};    ~b(){};    virtual void setn(int m_){k=m_;}    virtual void show(){cout<<k<<endl;}protected:    int k;};class c:public b{public:    c(){};    ~c(){};    void setn(int m_);    void show();private:    int d;};void c::setn(int m_){    d=m_;    b* p = (b*)this;    p->setn(m_);}void c::show(){    cout<<k<<endl;    cout<<d<<endl;}int main(){        c z;    z.setn(7);    z.show();    return 0;}

C/C++ code

void c::setn(int m_){    d=m_;    b* p = (b*)this;    p->setn(m_);}
[解决办法]
C/C++ code
void c::setn(int m_){    d=m_;    b* p = (b*)this;    p->b::setn(m_);}