Function | Package: util.date-time | ToC | DocOverview | CGDoc | RelNotes | FAQ | Index | PermutedIndex
| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version

## subtract-duration

Arguments: date-timespec durationspec

Returns a new `date-time` object obtained by subtracting the `duration` specified by durationspec from the `date-time` specified by date-timespec.

The default method does not subtract two `duration`s.

     > (require :datetime)
     > (use-package :util.date-time)

     > (subtract-duration (date-time "1985-04-10T10:30:40")
             (duration "1MT1H4S"))
     #<date-time "1985-03-10T09:30:36" @ ...>

See duration, date-time, and add-duration.

See date-time.htm for information on support in Allegro CL for parsing and generating time expressions using the ISO 8601 standard. See particularly the section Adding/Subtracting Durations, where it is pointed out (with examples) that adding and subtracting durations are not inverse operations and adding durations is not associative.

Copyright (c) 1998-2019, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.2 page.
Created 2012.5.30.

|  | ToC | DocOverview | CGDoc | RelNotes | FAQ | Index | PermutedIndex
| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version