Question

How do I compare two timestamps with format yyyy-mm-dd hh-mm-ss to get the total difference in minutes?

The timestamps are retrieved from MySQL. So far I’ve tried using time_t or even breaking down the whole string to compare but the problem with the latter is it doesnt recognize the difference in days.

thanks in advance!

edit1:
by comparing the timestamps i need to check whether the difference is bigger than x minutes.

like:

timestamp1 = getTimestampFunction1();
timestamp2 = getTimestampFunction2();

difference = timestamp1 - timestamp2; //difference in minutes

if (difference > 60)
{
    do this;
}
else
{
    do that;
}  

Answer 1

This can be done with boost

#include <boost/date_time/local_time/local_time.hpp>

#include <string>
using namespace std;
using namespace boost::local_time;
using namespace boost::posix_time;

class DateTimeDiff {
    istringstream ss;
    local_time_input_facet* facet;
public:
    DateTimeDiff(char const * format)
    : facet(new local_time_input_facet(format)) {
        ss.imbue(locale(ss.getloc(), facet));
    }
    double delta_minutes( string t0, string t1 ) {
        local_date_time ldt0(not_a_date_time), ldt1(not_a_date_time);
        ss.str(t0); ss >> ldt0;
        ss.str(t1); ss >> ldt1;
        return time_duration(ldt1 - ldt0).total_seconds() / 60.0;
    }
};

int main() {
    DateTimeDiff dt("%Y-%m-%d %H-%M-%S");

    const string t0 = "2013-01-02 13-14-27",
                 t1 = "2013-02-01 12-56-09";

    double diff = dt.delta_minutes(t0,t1);

    cout << t0 << " and "
         << t1 << " are "
         << diff << " minutes apart."
         << endl;

    cout << diff << " minutes is ";
    if (diff > 60) {
        cout << "more than";
    } else {
        cout << "less than or equal to";
    }
    cout << " one hour." << endl;

    return 0;
}

The output is

2013-Jan-02 13:14:27 UTC and 2013-Feb-01 12:56:09 UTC are 43181.7 minutes apart.
43181.7 minutes is more than one hour.