我试了好久都有问题，编译不能通过，说无法访问point类中的a和c。望各位帮指正、
#include<iostream>
using namespace std;
class sh;
class point
{
private:
    int a;
public:
    int b;
    point(int pa,int pc)
    {
        a=pa;
        c=pc;
    }
    friend void sh::showp(point &);
protected:
    int c;
};
class sh
{
private:
    int s;
public:
    void showp(point &);
};
void sh::showp(point &bo)
{
    cout<<bo.a<<"\t"<<bo.c<<endl;
}
int main()
{
    point bo(29,89);
    bo.showp(bo);
    return 0;
}