有关“类”的经典错误

//用输入和输出函数，为类t1赋值并输出#include<iostream>using namespace std;class Time{public: int hour; int minute; int sec;};
int main(){ Time t1; void set_time(Time  t); void show_time(Time t); set_time(t1); show_time(t1); return 0;}void  set_time(Time t){ cin >> t.hour; cin >> t.minute; cin >> t.sec;}void show_time(Time t){ cout << t.hour << ":"  << t.minute << ":" << t.sec << endl;}