重载>(friend必须吗？).
#include <iostream>using namespace std;
class position
{
public: position(int m,int n); friend ostream & operator <<(ostream & out,const position & s); friend istream & operator >>(istream & in,position & s); int x; int y;
};void main(){ position m(3,4); cout<<m<<endl; cout<<"输入x,y\n"; cin>>m; cout<<m<<endl;}position ::position(int m,int n) :x(m),y(n){}ostream & operator<< (ostream & out,const position & s){ out<<"(" << s.x<<","; out<<s.y << ")\n"; return out;}istream & operator>> (istream & in,position & s){ in>>s.x; in>>s.y; return in;}