Re: How to subtract timestamp in elisp?

[stardiviner]

Emanuel Berg via Users list for the GNU Emacs text editor 
<help-gnu-emacs@gnu.org> writes:

> stardiviner wrote:
>
>> I'm find an Elisp solution to subtract timestamps
>> like "00:12:35".
>>
>> I hope a function can subtract two timestamps:
>>
>>     00:12:35 - 00:10:45 = 00:01:50
>
> Here are there functions that might be what you look
> for, or be interesting to check out at least:
>
> ;;; -*- lexical-binding: t -*-
> ;;;
> ;;; this file:
> ;;;   http://user.it.uu.se/~embe8573/emacs-init/time-cmp.el
> ;;;   https://dataswamp.org/~incal/emacs-init/time-cmp.el
>
> (defun wall-clock-time (h1 m1 s1 h2 m2 s2)
>   (let*((d   08) ; arbitrary day to use below, any would do
>         (m   05) ; actually something cool happened that day
>         (y 1978) ; in the history of climbing
>         (total-seconds-1 (float-time (encode-time s1 m1 h1 d m y)))
>         (total-seconds-2 (float-time (encode-time s2 m2 h2 d m y)))
>         (s-diff (- total-seconds-2 total-seconds-1)) )
>     (format-seconds "%.2h:%.2m:%.2s" s-diff) ))
> (defalias 'wct #'wall-clock-time)
> ;; (wct 09 35 10 23 00 00) ; 13:24:50
> ;; (wct 09 35 10 09 35 20) ; 00:00:10
>
> (defun time-between-times (year1 month1 day1
>                            year2 month2 day2)
>   (let*((seconds-then  (float-time (encode-time 0 0 0 day1 month1 year1)))
>         (seconds-now   (float-time (encode-time 0 0 0 day2 month2 year2)))
>         (seconds-diff  (- seconds-now seconds-then)) )
>     (format-seconds "%yy %dd" seconds-diff)))
> ;;   (time-between-times 1958  4 13 1958 8 30) ; Tahiti Nui 2 -> 3,
> ;;                                             ; i.e. 0y 139d
>
> (defun get-time-since (year month day)
>   (interactive "nyear: \nnmonth: \nnday: ")
>   (message "%s"
>            (format-seconds
>             "%yy %dd"
>             (float-time
>              (time-since (encode-time 0 0 0 day month year)) ))))
> ;; (get-time-since 2011 09 27) ; 8y 228d @ 2020-05-10

Thanks, learned more about time handling functions and code.

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[ stardiviner ]
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