#include <iostream>
#include <ctime>

int main()
{
    // time: 16 00 26
    // date: 11 02 13
    std::tm time2013;
    time2013.tm_hour = 16;
    time2013.tm_min = 00;
    time2013.tm_sec = 26;
    time2013.tm_mday = 11;
    time2013.tm_mon = 2-1;
    time2013.tm_year = 113;

    // time: 00 00 00
    // date: 01 01 1970
    std::tm time1970;
    time1970.tm_hour = 00;
    time1970.tm_min = 00;
    time1970.tm_sec = 00;
    time1970.tm_mday = 01;
    time1970.tm_mon = 1-1;
    time1970.tm_year = 70;

    std::cout << std::fixed 
        << std::difftime( std::mktime(&time2013), std::mktime(&time1970) ) << '\n' ;
}