use g++ to compile

include <iostream>

using namespace std;
class Time
{
public:
int hour;
int minute;
int sec;
};
int main( )
{
void set_time(Time&,int hour=0,int minute=0,int sec=0);//函数声明
void show_time(Time&);//函数声明
Time t1;
set_time(t1,12,23,34);//通过实参传递时、分、秒的值
show_time(t1);
Time t2;
set_time(t2);//使用默认的时、分、秒的值
show_time(t2);
return 0;
}
void set_time(Time& t,int hour,int minute,int sec)
{
t.hour=hour;
t.minute=minute;
t.sec=sec;
}
void show_time(Time& t)
{
cout<<t.hour<<":"<<t.minute<<t.sec<<endl;
}