C++中结构体函数的实现

#include <iostream>  
struct travel_time  
{  
    int hours;  
    int mins;  
};  
const int Mins_per_hr = 60;  
  
travel_time sum(travel_time t1, travel_time t2);  
void show_time(travel_time t);  
  
int main()  
{  
    using namespace std;  
    travel_time day1 = {5, 45};    // 5 hrs, 45 min  
    travel_time day2 = {4, 55};    // 4 hrs, 55 min  
  
    travel_time trip = sum(day1, day2);  
    cout << "Two-day total: ";  
    show_time(trip);  
  
    travel_time day3= {4, 32};  
    cout << "Three-day total: ";  
    show_time(sum(trip, day3));  
    // cin.get();  
  
    return 0;  
}  
  
travel_time sum(travel_time t1, travel_time t2) 
{  
    //结构作为函数参数直接传入
    travel_time total;  
  
    total.mins = (t1.mins + t2.mins) % Mins_per_hr;  
    total.hours = t1.hours + t2.hours +  
                 (t1.mins + t2.mins) / Mins_per_hr;  
    return total;
    //结构体作为结果被传出
}  
  
void show_time(travel_time t)  
{  
    using namespace std;  
    cout << t.hours << " hours, "  
         << t.mins << " minutes\n";  
}