HOWTO: Find the Day that Daylight Savings Time Occurs

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a, 6.0
• Microsoft FoxPro for Windows, versions 2.5, 2.5a, 2.5b, 2.6, 2.6a
• Microsoft FoxPro for Macintosh, versions 2.5b, 2.5c, 2.6a
• Pro Edition of Microsoft Visual FoxPro for Mac, version 3.0

SUMMARY

Under legislation enacted in 1986, Daylight Savings time in the United States (U.S.) begins at 2 A.M. on the first Sunday of April and ends at 2 A.M. on the last Sunday of October. The sample code in the MORE INFORMATION section determines what day in April the first Sunday occurs and on and what day in October the last Sunday occurs for each year.

MORE INFORMATION

Sample Code

   * Note that bdate and edate are assigned the first day of April and the
   * last day of October in this example. You would want to change these
   * variables to be equal to the DATE() function in a real situation.

      CLEAR

      IF "6.00"$VERSION(1)
         oldstrictdate = SET("STRICTDATE")
         SET STRICTDATE TO 0
      ENDIF

      bdate = {04/01/98}  && Change year to check other dates,
      edate = {10/31/98}  && use the DATE() function for real time.
      y = ""
      IF MONTH(bdate) = 4 AND DAY(bdate) < 8  && First week of April.
         * Need first day of month and current year, change to DATE().
         bsavings = CTOD('04/01/' + ALLTRIM(STR(YEAR(BDATE))))
        =getnum(CDOW(bsavings)) && Get number to add to first day of April.
         ? "Daylight Savings Time starts on Sunday - "
         ?? bsavings + VAL(SUBSTR(y,1,1))
         ? "The first day of April is: "
         ?? CDOW(bsavings)
      ENDIF

      IF MONTH(edate) = 10 AND DAY(edate) > 24  && Last week of October.
         * Need last day of month and current year, change to DATE().
         esavings = CTOD('10/31/' + ALLTRIM(STR(YEAR(EDATE))))
         =getnum(CDOW(esavings))  && Get number to subtract from 10/31.
         ? "Daylight Savings Time ends on Sunday - "
         ?? esavings - VAL(SUBSTR(y,2,1))
         ? "The last day of October is: "
         ?? CDOW(esavings)
      ENDIF

      IF "6.00"$VERSION(1)
         SET STRICTDATE TO &oldstrictdate
      ENDIF

      PROCEDURE getnum
      PARAMETER dayvar

      DO CASE
         CASE dayvar = "Sunday"
         y='00'
         CASE dayvar = "Monday"
         y='61'
         CASE dayvar = "Tuesday"
         y='52'
         CASE dayvar = "Wednesday"
         y='43'
         CASE dayvar = "Thursday"
         y='34'
         CASE dayvar = "Friday"
         y='25'
         CASE dayvar = "Saturday"
         y='16'
      ENDCASE

   ********************* End of code ******************* 

Additional query words: kbvfp600

Keywords :
Version : MACINTOSH:2.5b,2.5c,2.6a,3.0; WINDOWS:2.5,2.5a,2.5b,2.6,2.6a,3.0,3.0b,5.0,5.0a,6.0
Platform : MACINTOSH WINDOWS
Issue type : kbhowto