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- Path: fido.asd.sgi.com!austern
- From: Max TenEyck Woodbury <mtew@cds.duke.edu>
- Newsgroups: comp.std.c++
- Subject: Time representations
- Date: 30 Jan 1996 20:24:13 PST
- Organization: Duke University Center for Demographic Studies
- Approved: austern@isolde.mti.sgi.com
- Message-ID: <4emq2k$ecu@news.duke.edu>
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- Originator: austern@isolde.mti.sgi.com
-
- The C++ standard incorporates the C standard for dates and times
- by reference. There are at least three problems with the 'struct tm'
- definition in that standard.
-
- First, the range specified for tm_sec is 0-59. While this is the
- normal range for almost all minutes, there are officially 'leap
- seconds' that are declared from time to time. The standard should
- reflect this possibility, even if it is almost always ignored in
- practice.
-
- Second, there are cultures that operate on a lunar calendar,
- rather than on the Gregorian calendar. They have 13 or more months
- a year. The tm_mon range needs to reflect this.
-
- Third, there are cultures that do not start their year on January
- 1st. This has an impact on the definition of tm_yday even though
- its range will not change. There is a similar definitional problem
- with tm_year.
-
- There may also be a problem with tm_wday. I vaguely remember
- hearing about cycles of 17 or 19 days used in some cultural contexts
- that might have been in addition to or in place of the weekly cycle,
- but I can not remember the exact context.
-
- Max
- ---
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