求助!!! 不能运行帮我纠正.
#include<iostream.h>
class exe{
private: int x;
public: df(int a)
        {x=a;}
        void show()
        {
        cout<<x<<endl ;    
        }
};
void main()
{
exe pp,*b ;
pp.df(5);
b=&pp;
b.show();
return 0;
}