C ++两次之间的时差

Question

The objective of this program is to calculate the time difference between a start time and an end time.

The start and end time will be entered as an 4-digital integer, and the time difference will need to be computed. The inputted times are represented as hh:mm, without the ":".

Example: 
first time: 0800
second time: 1755
Time elapsed: 9 hr and 55 min

This is the code I have:

int main()
{

int first_time;
int second_time;
int dif_time;
double mod_time;

cout<<"Enter first time" << endl;
cin>>first_time;

cout<<"Enter second time" << endl;
cin>>second_time;

dif_time = second_time - first_time;

mod_time = dif_time % 60;

std::cout << "Time elapsed: " << dif_time << " hours" << mod_time << " minutes" << endl;

}

The problem is that it does output the time in hours correctly. Any suggestions on how to improve this program would be greatly appreciated.

Answer 1

Would probably be better to convert everything in minutes, calculate the difference and then convert to hours and minutes:

#include <iostream>

int main() 
{
    int first_time;
    int second_time;

    std::cout << "Enter first time" << std::endl;
    std::cin >> first_time;

    std::cout << "Enter second time" << std::endl;
    std::cin >> second_time;

    int first_time_min = first_time / 100 * 60 + first_time % 100;
    int second_time_min = second_time / 100 * 60 + second_time % 100;
    int diff_time_min = second_time_min - first_time_min;

    std::cout << "Time elapsed: " << diff_time_min / 60 << " hours " << diff_time_min % 60 << " minutes" << std::endl;
}

Answer 2

Possible solution:

#include <iostream>

int main() {
    int first_time;
    int second_time;
    int dif_time_in_minutes;
    int hours, minutes;

    std::cout << "Enter first time:";
    std::cin >> first_time;

    std::cout << "Enter second time:";
    std::cin >> second_time;

    dif_time_in_minutes = (second_time / 100)*60 + (second_time % 100) - 
        (first_time / 100) * 60 + (first_time % 100);

    hours = dif_time_in_minutes / 60;
    minutes = dif_time_in_minutes % 60;

    std::cout << "Time elapsed: " << hours << " hours " << minutes << " minutes" << std::endl;
}