Anastasia Gornostaeva wrote:
> open Unix
> 
> let _ =
>    let curr_time = time () in
>    let curr_tm = gmtime curr_time in
>    let new_time, _ = mktime {curr_tm with tm_hour = curr_tm.tm_hour+1} in
>    let diff = new_time -. curr_time in
>       Printf.printf "%f\n%f\n%f\n"
> 	 curr_time
> 	 new_time
> 	 diff
> 
> 
> gives an negative result -7200.000000. Why?

Form the manual:

gmtime : Assumes UTC (Coordinated Universal Time), also known as GMT.

mktime : The tm argument is interpreted in the local time zone.

So, actually you compare GMT with your local time zone, which in my case 
(Germany) returns 0 for the above example.


Try localtime instead of gmtime:

localtime : Assumes the local time zone.


	Alex