CFLib.org – Common Function Library Project

Description:
Returns the date for The start of Daylight Saving Time for a given year. If no year is specified, defaults to current year.

Return Values:
Returns a date object.

Example:

<CFOUTPUT>
This year, Daylight Saving Time starts on #DateFormat(GetDaylightSavingTimeStart(), 'dddd, mmm dd, yyyy')#.
</CFOUTPUT>

Parameters:

Full UDF Source:

/**
 * Returns the date for The start of Daylight Saving Time for a given year.
 * This function requires the GetNthOccOfDayInMonth() function available from the DateLib library.
 * 
 * @param TheYear      Year you want to return the start of Daylight Saving Time. (Optional)
 * @return Returns a date object. 
 * @author Ken McCafferty (mccjdk@yahoo.com) 
 * @version 2, December 20, 2006 
 */
function getDaylightSavingTimeStart() {
    var TheYear=Year(Now());
      if(ArrayLen(arguments)) TheYear = arguments[1];
    //US Congress changed it for 2007,may switch back
    // From first Sunday in April to Second Sunday in March 
    if(TheYear lt 2007) return CreateDate(TheYear,4,GetNthOccOfDayInMonth(1,1,4,TheYear));
    else return CreateDate(TheYear,3,GetNthOccOfDayInMonth(2,1,3,TheYear));
}