Q106690: Function for Returning a Julian Date in FoxPro

Article: Q106690
Product(s): Microsoft FoxPro
Version(s): MS-DOS:2.0,2.5,2.5a,2.5b; WINDOWS:2.5,2.5a,2.5b,3.0
Operating System(s): 
Keyword(s): kbcode
Last Modified: 05-FEB-2000

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0 
- Microsoft FoxPro for MS-DOS, versions 2.0, 2.5, 2.5a, 2.5b 
- Microsoft FoxPro for Windows, versions 2.5, 2.5a, 2.5b 
-------------------------------------------------------------------------------

SUMMARY
=======

The FoxPro functions SYS(1) and SYS(11) return a Julian day number, which is
different from a Julian date. To return a Julian date, you can write a
user-defined function (UDF), as described below.

MORE INFORMATION
================

SYS(1) and SYS(11) return a date according to the Julian calendar, in which each
day is counted, with day 1 being in 4713 B.C. On the other hand, a Julian date
is a date represented by a five-digit number, the first two digits being the
last two digits of the year, and the final three digits being the number of days
that have elapsed since January 1 of that year. For example, 01/01/93 according
to the Julian calendar is 2448989, whereas the Julian date is 93001.

The following program calls a UDF that converts a date in FoxPro date format to a
Julian date.

     * Begin program
     @1,1 SAY "Enter a date" GET testdate DEFAULT {  /  /  }
     READ
     @2,1 SAY "The Julian Date of "+ DTOC(testdate) + " is " ;
        + TRANSFORM(julian(testdate),'99999')
     *End program

     FUNCTION julian
     PARAMETER tdate

     *isolate the year and convert it to a string
     cYear = RIGHT(DTOC(tdate),2)
     firstjan = CTOD("01/01/" + cYear)

     *calculate the sequential number of the day
     jday = tdate-firstjan+1

     *position the year at the two leftmost digits
     nYear = VAL(cYear) * 1000

     *combine year and day number
     jdate = nYear + jday

     RETURN jdate
     *End Function julian

Additional query words: VFoxWin FoxDos FoxWin format

======================================================================
Keywords          : kbcode 
Technology        : kbVFPsearch kbAudDeveloper kbFoxproSearch kbZNotKeyword3 kbFoxPro200DOS kbFoxPro250DOS kbFoxPro250aDOS kbFoxPro250bDOS kbFoxPro250 kbFoxPro250a kbFoxPro250b kbVFP300
Version           : MS-DOS:2.0,2.5,2.5a,2.5b; WINDOWS:2.5,2.5a,2.5b,3.0

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.