13[分析题]
#include ”iostream.h”class three{ int x,y,z; public: three(int a,int b,int c){ x=a;y=b;z=c;} friend ostream &operator<<(ostream &output, three ob); };ostream &operator<<(ostream &output, three ob){    output<<ob.x<<’,’<<ob.z<<’,’<<ob.y<<endl;    return output;}main(){    three obj1(10,20,30);   cout<<obj;    three obj2(50,40,100);cout<<obj2; }