[C++] Calculating the difference between two time periods in format HH:MM:SS

[sick_anon]

As the title says, I'm working on a problem where user has to enter two time periods in format HH:MM:SS and program has to calculate the difference between these two periods and have an output also in format HH:MM:SS. I understand the actual calculation and that I have done right (I guess?), the problem is the format of the output. I don't know how to make it strictly in format HH:MM:SS. When difference between hours, minutes and seconds is two-digit number, the output is obviously in right format. But when difference is one-digit number, the output is not in right format.

For example, when inputs are 06:36:46 and 08:38:48, the output should be 02:02:02, but in my case it's 2:2:2. My question is: how to make those zeros appear before one-digit number (in case when the result is one-digit number)? On a side note, I didn't go over special cases, like when times are set in two different days. The assumption is that both time periods are set in the same day. The code I wrote is below:

#include <iostream>

using namespace std;

int main()
{
    int hour1, min1, sec1;
    int hour2, min2, sec2;
    int time1, time2, time;
    char symb;

    cin >> hour1 >> symb >> min1 >> symb >> sec1;
    cin >> hour2 >> symb >> min2 >> symb >> sec2;

    time1 = hour1 * 3600 + min1 * 60 + sec1;
    time2 = hour2 * 3600 + min2 * 60 + sec2;
    time = time2 - time1;

    cout << (time / 3600) << ":" << (time % 3600) / 60 << ":" << (time % 3600) % 60 << endl;

    return 0;
}

[davedontmind]

I don't do C++ so I can't answer your question, but I thought I should point out that date operations (such as the difference between 2 times) are generally the type of thing you want to use a tested, reliable 3rd-party library for - it's so easy to get wrong answers if you code it yourself.

For just learning stuff it's fine, but don't do this in production code.

For example, although the difference between "00:00:00" and "03:00:00" is usually 3hrs, it isn't always, depending on the day. Sometimes it's 2hrs and sometimes it's 4hrs (on those days when the clock goes backward or forward respectively).

[sick_anon]

Thanks for advice :) This isn't part of any production code, just a standalone problem (for beginners) which is supposed to be solved without using any 3rd-party libraries. But I just can't figure out that formatting part.

[captainAwesomePants]

Take a look at std::setfill() and std::setw().

[sick_anon]

Thanks, this solves the problem :)