DATECONV
Автор: Russel Brooks
Дата: 1998
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! DATECONV HELP v7.0 !
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Purpose:
Convert a date from one format to another format and optionally offset
the date some number of days. The caller specifies the format of the
input date, and optionally the format of the output date. If not
specified, the output will default to the form "dd Mmm yyyy" (like
REXX's Date() function). The input date is validated so Dateconv() can
be used to check a date even if date conversion isn't required.
Date_Out = DATECONV( Date_In, Format_In <,Format_Out> <,CC> <,Offset> )
Where:
Date_In ...... The date you want to convert to another form,
or just validity check.
Format_In .... identifies the format of the input date.
Format_Out ... Optional. Defaults to "N".
identifies the format(s) wanted for the output.
CC ........... Optional Century override. Must be 2 digits: 01-99.
Allows user to override the default century assigned to
input date formats with 2 digit years (and Date(C) too.)
Offset ....... Optional. Defaults to zero offset.
Causes output date to be shifted this number of days.
Form is +n or -n where "n" is a whole number of days to
shift the output date.
If any Errors are encountered a null string will be returned.
"CC" can affect output date
Allowable Format_In: -----
B- Basedate ................ dddddd No
C- days this Century ........ ddddd Yes
D- Days this year ............. ddd No
E- European .............. dd/mm/yy Yes
J- Julian ................... yyddd Yes
N- Normal ............. dd Mmm yyyy No
O- Ordered ............... yy/mm/dd Yes
S- Sorted ................ yyyymmdd No
U- USA ................... mm/dd/yy Yes
I- ISO ................. yyyy-mm-dd No
note: Month name, Weekday name, LeapYear and "*" are NOT valid *IN* formats.
Allowable Format_Out:
B- Basedate ................ dddddd
C- days this Century ........ ddddd
D- Days this year ............. ddd
E- European .............. dd/mm/yy
J- Julian ................... yyddd
M- Month .......... (name-of-month)
N- Normal ............. dd Mmm yyyy ** Default **
O- Ordered ............... yy/mm/dd
S- Sorted ................ yyyymmdd
U- USA ................... mm/dd/yy
W- Weekday ...... (day-of-the-week)
I- ISO ................. yyyy-mm-dd
L- LeapYear ....... 1(yes) or 0(no)
*- Combination .... variable output default: "NBSMWDJCOEULI"
Arg(3) "Format_Out"
--------------------
Normally only the first character of Format_Out matters. If the first
character of Format_Out is "*" then the rest of the letters of
Format_Out are significant. Date_Out will be ALL the date formats in
the order specified by the letters in Format_Out. If only "*" is
specified it is the same as "*NBSMWDJCOEULI" which is all date formats
supported. If additional date formats are added in the future (very
unlikely) then I expect they will also be added to the string of dates,
on the end, so that while the string data would change it will still
parse correctly. Using Format_Out "*" to get multiple date forms in a
single call is much quicker than having to call DATECONV once for each
format wanted.
Default Century
----------------
For date formats U, E, O, and J which only have 2 digit years, the
default century is chosen by using a 100 year sliding window similar
to Rexx's Date() function. Date(C) defaults to the current century.
Arg(4) "CC"
------------
The (optional) 4th argument is used to override the default century
assigned date formats U, E, O, J and C. It must 2 digits, 01-99.
June 1998 v7.0: For dates with 2 digit years Dateconv now picks a
suitable default century by using a 100 year sliding window similar to
Rexx's Date(). Previously the current century was used.
Special case:
--------------
If Arg(1) Date_In and Arg(2) Format_In are left blank then the input
will be "TODAY" (which Dateconv doesn't have to validity check).
This is useful if you need a date offset from today and/or you need
Format_Out "L" or "I" which are not directly available with REXX's
Date() function.
Dateconv History:
------------------
Dateconv() ORIGINALLY duplicated the operation of the Dateconv()
function that is included with Personal REXX. Personal REXX is a
product of Quercus Systems (and was previously sold by Mansfield
Software).
Since then additional function has been added to 'my' Dateconv() so it
is no longer identical in operation to the Personal REXX function. At
this time Personal REXX code using Dateconv() that is ported to IBM and
uses my Dateconv() should work ok. However moving code TO Personal REXX
could cause problems if it uses any of the function that I have added to
Dateconv().
The Dateconv() extensions are: Arg(4), Arg(5), Format_In/Out "I",
Format_Out "L", Format_Out "*", and allowing the input date to default
to today.
The internal logic is all mine, only the original command format was
borrowed from Personal REXX's Dateconv().
Dateconv() is written as a PROCEDURE to be included inside any REXX code
that needs it. I supply it as an EXEC which is just the Procedure file
with a small front end so it can run as an external function. If you
need the Procedure then copy it from the exec without the exec front
end. The advantage to leaving it external is you won't need to update
your code if Dateconv() is replaced. The disadvantage is slower speed
if you call it repeatedly.
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Examples:
Convert a Date(USA) date to Date(Sorted) form.
say dateconv('11/15/51',U,S) /* 19511115 then 20511115 */
Note: The 100 year sliding window that provides the missing century in
the input date will cause the output date to change from 1951 to
2051 in the fall of 2001.
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Convert a Date(Ordered) date to the default output form.
say dateconv('51/11/15',O) /* 15 Nov 1951 */
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What is the English month name of this date?
Convert a Date(USA) date to Date(Month) form.
say dateconv('11/15/51',U,M) /* November */
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What is the English weekday name of this date?
Convert a Date(Normal) date to Date(Weekday) form.
say dateconv(15 Nov 1951,N,W) /* Thursday */
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What is the English weekday name two days before this date.
Convert a Date(Sorted) date to Date(Weekday) form with offset.
say dateconv(19511115,S,W,,-2) /* Tuesday */
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Offset this Date(USA) date two days earlier but don't change format.
say dateconv('11/15/51',U,U,,-2) /* 11/13/51 */
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Override the default century selected when input doesn't include century.
say dateconv('15/11/95',E,S,18) /* 18951115 */
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Is this Date(Sorted) date within a Leap Year? 1=Yes/0=No
say dateconv(19511115,S,L) /* 0 */
say dateconv(20001115,S,L) /* 1 */
The following routine is what Dateconv uses to find Leapyear. If you
have a 4 digit year you could use it too and avoid the overhead of
calling Dateconv.
select
when yyyy // 4 > 0 then leap_year = 0
when yyyy // 100 > 0 then leap_year = 1
when yyyy // 400 = 0 then leap_year = 1
otherwise leap_year = 0
end
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Dateconv() indicates an error condition by returning null.
You can't convert FROM Date(Weekday) or Date(Month) or Date(Leapyear).
dx = dateconv(Saturday,W,U)
if dx = '' then say 'Error detected' /* test for (null) */
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Dateconv() gives you Date(Iso) format that isn't available from REXX's Date().
What is the Date(Iso) date?
say dateconv(,,I)
You could also use the following Translate routines to convert to/from
ISO date format.
/* convert Date(Sorted) to ISO date */
s2i: Return translate('CcYy-Mm-Dd',arg(1),'CcYyMmDd')
/* convert ISO date to Date(Sorted) */
i2s: Return translate('CcYyMmDd' ,arg(1),'CcYy-Mm-Dd')
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Does this date look valid? No conversion is needed.
if dateconv(date,format) = '' then say 'Invalid date'
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Dateconv() can return multiple date formats. The letters after the "*"
specify the output formats wanted and their order.
parse value dateconv(,,'*ULW',,'+1') with USAdate LeapYear Weekday .
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Dateconv() can return multiple date formats. If no letter follows "*"
then return ALL supported date formats.
Note: the default date format needs to be put back together after parsing.
parse value dateconv(,,'*',,'-1') with N1 N2 N3 B S M W D J C O E U L I .
N = n1 n2 n3
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How can I test for the day of the week without using the English
Day of the Week names?
dow = (date('B')+1)//7 /* 0:Monday ... 6:Sunday */
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How many days are there between 2 dates?
First convert both dates to Basedate format and then subtract.
The following example will calculate the number of days from TODAY
until New Years Eve. (Party time])
party = dateconv(left(date('S'),4)1231,S,B) - date(B)
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Got a good example (or want one) for a situation not covered?
Send me the details and I'll consider adding it.
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Russel Brooks rlbrooks@us.ibm.com (aka: rlbrooks@pobox.com)