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The LA Fox Developer Newsletter
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March 1996
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by Gunter C. Mayer CompuServeID: 74163,2215
A patch for the PC Systems Date and a Function to control the limits of Foxpro Date Handling after Y-1 999.
By now most FP Developers must have heard or read tidbits of grave Millennium Warnings concerning Y-2000 Date Handling, all super alarming, but ALL without specific answers. Having authored two very Date sensitive Applications, which are in intense daily use, I naturally started to wonder how this would affect my life on New Years Day 2000. Like do I have to stick around??
So I decided to spend some time on this subject and came up with some very interesting discoveries AND a clean solution, in the form of a Date Function MCDATEO, which I want to share.
1.0 DEFINING THE PROBLEMS
FP Applications written in 2.5, 2.6 and Visual Foxpro all share
the same Date Processing Fundamentals embedded in its
Functions and Defaults. Here are the main areas of concern:
the FP Date() Function.
Default of 1900-
1999.
ignoring Picture Clauses.
tions.
Date), versus “historical” Dates, which would fall outside the FP Default Century.
It has been alarmingly reported, that the PC World, as we know
it,
will come to an end at midnight Dec. 31, 1999, with 99% of present day PC’s going nuts, especially when the power is off. The problem lies with the CMOS Clock Chip and in the DOS! Windows OP Systems, which sound-ed fatal to me, until I found YEAR2000.ZIP on the Web.
It contains YEAR2000.TXT and YEAR2000. EXE, which patches the transition flaw. I installed and tested it and it works. Thanks to GT Becker, Dallas TX.
My conclusion: Set Century introduces complications that can be avoided. The most important feature here is that this switch primarily affects the Format of
recording
of Date Entries, the Date Entry Format and the attachment of the Century Indicator to the Date, whether the actual or the FP Default Century Indicator is attached. Did you know that this setting also over rides your Picture Clauses of Date Boxes?
OFF: Records the Date
in
[MM/DDIYY] Format. FP adds its embedded Default Century Indicator of 1900- 1999 as if there
was no tomorrow
, and it also ignores any Century Indicator
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added to the Date Entry.
When
later set to ON, all Years default to the 20th Century Indicator, thusthe Year [/21] will become 1921.
ON: Records the Date in [MM/DD/CCYY] Format. When later set to OFF, the display Format becomes [MM/DD/YY], but the actual, not the default Century Indicator, is used in Date Calculations.
1.3 Picture Clauses:
Here is the first Grande Surpriso for me!
They are totally ignored when displaying an
©
GET {DATE} Field. FP crudely pops its default Date Box Size onto your form. OFF furnishes an 8 digit, ON a 10 digit Date Box, adding that almighty 2 digit Century Indicator without regard to Real Estate crowding or overlap. For example...
Set Century ON.
@GET dDATE Pict ‘99/99/99’
Bingo, the resulting display is ‘MM/DD/CCYY.
Conclusion: Without a Function, some major rework might be
required here! This has a definite affect on your Screen Real
Estate. For specific [CCYY] Date Entries I may have to [Set
Cent ON] before the
@
GET.
1.4 Century Ranges of FP Date Functions
To start with, a refresher of the confusing Century Date Ranges of Foxpro Date Commands, and later an individual look at things.
2.0 Review of DP Date Functions
2.1 Foxpro Systems Date [DATEO]:
It takes its values from the internal PC Date Clock. It can NOT
be changed from within FP, but no problem, our little EXE File
has this one handled OK.
2.2 Date Functions (Assuming the
20th Century):
In my opinion, FP has over restricted some of the flexibility that might be expected by developers. The Default Century Indicator (100 year Range) should be programmable in the Config.FP File, for example 1950 to 2049 and it definitely should stay the heck out of my picture clauses. After testing, I created two categories for these Puppies:
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