+\f
+;;;###autoload
+(defun format-seconds (string seconds)
+ "Use format control STRING to format the number SECONDS.
+The valid format specifiers are:
+%y is the number of (365-day) years.
+%d is the number of days.
+%h is the number of hours.
+%m is the number of minutes.
+%s is the number of seconds.
+%z is a non-printing control flag (see below).
+%% is a literal \"%\".
+
+Upper-case specifiers are followed by the unit-name (e.g. \"years\").
+Lower-case specifiers return only the unit.
+
+\"%\" may be followed by a number specifying a width, with an
+optional leading \".\" for zero-padding. For example, \"%.3Y\" will
+return something of the form \"001 year\".
+
+The \"%z\" specifier does not print anything. When it is used, specifiers
+must be given in order of decreasing size. To the left of \"%z\", nothing
+is output until the first non-zero unit is encountered.
+
+This function does not work for SECONDS greater than `most-positive-fixnum'."
+ (let ((start 0)
+ (units '(("y" "year" 31536000)
+ ("d" "day" 86400)
+ ("h" "hour" 3600)
+ ("m" "minute" 60)
+ ("s" "second" 1)
+ ("z")))
+ (case-fold-search t)
+ spec match usedunits zeroflag larger prev name unit num zeropos)
+ (while (string-match "%\\.?[0-9]*\\(.\\)" string start)
+ (setq start (match-end 0)
+ spec (match-string 1 string))
+ (unless (string-equal spec "%")
+ (or (setq match (assoc (downcase spec) units))
+ (error "Bad format specifier: `%s'" spec))
+ (if (assoc (downcase spec) usedunits)
+ (error "Multiple instances of specifier: `%s'" spec))
+ (if (string-equal (car match) "z")
+ (setq zeroflag t)
+ (unless larger
+ (setq unit (nth 2 match)
+ larger (and prev (> unit prev))
+ prev unit)))
+ (push match usedunits)))
+ (and zeroflag larger
+ (error "Units are not in decreasing order of size"))
+ (dolist (u units)
+ (setq spec (car u)
+ name (cadr u)
+ unit (nth 2 u))
+ (when (string-match (format "%%\\(\\.?[0-9]+\\)?\\(%s\\)" spec) string)
+ (if (string-equal spec "z") ; must be last in units
+ (setq string
+ (replace-regexp-in-string
+ "%z" ""
+ (substring string (min (or zeropos (match-end 0))
+ (match-beginning 0)))))
+ ;; Cf article-make-date-line in gnus-art.
+ (setq num (floor seconds unit)
+ seconds (- seconds (* num unit)))
+ ;; Start position of the first non-zero unit.
+ (or zeropos
+ (setq zeropos (unless (zerop num) (match-beginning 0))))
+ (setq string
+ (replace-match
+ (format (concat "%" (match-string 1 string) "d%s") num
+ (if (string-equal (match-string 2 string) spec)
+ "" ; lower-case, no unit-name
+ (format " %s%s" name
+ (if (= num 1) "" "s"))))
+ t t string))))))
+ (replace-regexp-in-string "%%" "%" string))
+
+