Week function gives wrong result for last week in year

Here is my general solution for my cfc which seems to work for all dates up to 2100 at least.

Hope it can help if you need a Week function to replace the CF one.

<cffunction name="getISOWeekNum" access="public" returntype="Numeric" hint="Gets ISO week number in which date occurs.">

    <cfargument name="date" type="date" required="true" hint="Date for which you wish to know the week number">

    <cfset var weeknum = 0>

    <cfset var isLeap = isLeapYear(Year(date))>

    <cfset var dayInWeek = dayOfWeek(date)>

    <cfset var isoDayOfWeek = iIf(dayInWeek GT 1, dayInWeek - 1, 7)>

    <cfset var nearestThur = dateAdd("d", 4 - isoDayOfWeek, date)>

    <cfset var fourthDayOfYear = createDate(year(nearestThur), 1, 4)>

    <cfset var fourthDayInWeek = dayOfWeek(fourthDayOfYear)>

    <cfset var fourthIsoDayOfWeek = iif(fourthDayInWeek GT 1, fourthDayInWeek - 1, 7)>

    <cfset var firstThur = dateAdd("d", 4 - fourthIsoDayOfWeek, fourthDayOfYear)>

    <cfset var lastWeek = iIf(fourthDayInWeek EQ 8 OR (isLeap AND fourthDayInWeek EQ 7), 53, 52)>

    <cfset var firstIsoDayOfFirstWeek = dateAdd("d", -(fourthIsoDayOfWeek-1), fourthDayOfYear)>

    <cfset var firstIsoDayOfLastWeek = dateAdd("d", -7, firstIsoDayOfFirstWeek)>

    <cfset var lastIsoDayOfFirstWeek = dateAdd("d", 6, firstIsoDayOfFirstWeek)>

    <cfset var weekDiff = iIf(dateCompare(date, firstIsoDayOfFirstWeek, "d") EQ -1, 0, 1)>

    <cfif dateCompare(date, firstIsoDayOfFirstWeek, "d") EQ -1 AND dateCompare(date, firstIsoDayOfLastWeek, "d") NEQ -1>

        <cfset weeknum = lastWeek>

    <cfelseif dateCompare(date, lastIsoDayOfFirstWeek, "d") NEQ 1 AND dateCompare(date, firstIsoDayOfLastWeek, "d") NEQ -1>

        <cfset weeknum = 1>

    <cfelse>

        <cfset weeknum = weekDiff + (dateDiff("d", firstThur, nearestThur) / 7)>

    </cfif>

    <cfreturn weeknum>

</cffunction>

Doug

Yeah, it's a known bug:

http://cfbugs.adobe.com/cfbugreport/flexbugui/cfbugtracker/main.html#bugId=80754

To work around, use Java:

<cfscript>

    oCalXmas = createObject("java", "java.util.GregorianCalendar").init(2011,11,25);

    writeOutput("Xmas day: #oCalXmas.get(oCalXmas.WEEK_OF_YEAR)#<br />");

    oCalBoxingDay = createObject("java", "java.util.GregorianCalendar").init(2011,11,26);

    writeOutput("Boxing day: #oCalBoxingDay.get(oCalBoxingDay.WEEK_OF_YEAR)#<br />");

</cfscript>

You might wanna go vote for the bug, too.

--

Adam