Date manipulation: Difference between revisions
added Emacs Lisp code for date manipulation
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(added Emacs Lisp code for date manipulation) |
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=={{header|Emacs Lisp}}==
<syntaxhighlight lang="lisp">
(defun fix-time-string (bad-string)
"If BAD-STRING has no space between time and a.m./p.m., add a space."
(replace-regexp-in-string "\\([[:digit:]]\\)\\([ap]\\)" "\\1 \\2" bad-string))
(defun adjust-if-pm (time-as-string)
"If TIME-AS-STRING includes pm/PM, and hour is 1 to 11, add 12 hours."
(let ((temp-time-stamp))
(setq temp-time-stamp (parse-time-string time-as-string))
(if (and (is-pm time-as-string) (is-hour-1-to-11 temp-time-stamp))
(decoded-time-add temp-time-stamp (make-decoded-time :hour 12))
temp-time-stamp)))
(adjust-if-pm "March 7 2009 7:30pm EST")
(defun is-pm (time-as-string)
"Test if TIME-AS-STRING has PM/pm in it."
(string-match-p "[Pp][Mm]" time-as-string))
(defun is-hour-1-to-11 (a-time-stamp)
"Test if hour in A-TIME-STAMP is between 1 and 11."
(let ((hour-value))
(setq hour-value (nth 2 a-time-stamp))
(and (>= hour-value 1) (<= hour-value 11))))
(defun add-hours (start-time-stamp number-of-hours)
"Add NUMBER-OF-HOURS to START-TIME-STAMP."
(decoded-time-add start-time-stamp (make-decoded-time :hour number-of-hours)))
(defun calc-future-time (string-calendar-date number-of-hours-in-future)
"Calculate future time by adding NUMBER-OF-HOURS-IN-FUTURE to STRING-CALENDAR-DATE ."
(let ((fixed-calendar-string)
(24-hour-calendar-string)
(decoded-future-time)
(coded-future-time))
(setq fixed-calendar-string (fix-time-string string-calendar-date))
(setq 24-hour-calendar-string (adjust-if-pm fixed-calendar-string))
(setq decoded-future-time (add-hours 24-hour-calendar-string number-of-hours-in-future))
(setq coded-future-time (encode-time decoded-future-time))
(format-time-string "%B %e %Y %R %p %Z" coded-future-time)))
</syntaxhighlight>
{{out}}
(calc-future-time "March 7 2009 7:30pm EST" 12)
<pre>
"March 8 2009 08:30 AM EDT"
</pre>
=={{header|Erlang}}==
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