hours and dates

[mathieu nacher]

hello, i am trying to substract 2 dates and times to obtain a duration. the 2 dates and the 2 times of day are separate. Before doing the substraction, which should be straightforward, how do i fuse date and time? thanks
here under are the 4 variables
Thank you!

* Example generated by -dataex-. For more info, type help dataex
clear
input int DAT1 double HOUR1 int DAT2 double HOUR2
23034 -1.8933732e+12 23034      -1893429120000
23031 -1.8934281e+12 23034 -1893412080000.0002
23034 -1.8934107e+12 23034 -1893406379999.9998
23087  -1.893447e+12 23087      -1.8934335e+12
    .              . 23076 -1893439559999.9998
23041 -1.8934026e+12 23042      -1893416940000
23054 -1.8934452e+12 23054 -1893400799999.9998
23035  -1.893411e+12 23036      -1.8934542e+12
23032 -1.8934488e+12 23035      -1893400440000
23037 -1.8933786e+12 23038      -1.8934539e+12
end
format %tdnn/dd/CCYY DATRUPT
format %tchh:MM HEURRUPT
format %tdnn/dd/CCYY DATNAISS
format %tchh:MM HRNAISS

[Clyde Schechter]

forvalues i = 1/2 {
    gen double date_time`i' = cofd(DAT`i') + HOUR`i'
    format date_time`i' %tc
}

As for calculating the difference, you may find the -clockdiff()- or -clockdiff_frac()- function more useful than subtraction, in that you can get an answer that is denominated in an appropriate time unit rather than another clock variable. (That's assuming you are using a relatively recent version of Stata that has those functions.)

[mathieu nacher]

thanks a lot!