CFLib.org – Common Function Library Project

Description:
CF returns weeknumbers that are not according to the ISO standard. This UDF does.

Return Values:
Returns a number.

Example:

ISOWeek(dateObject)<cfloop index="x" from=1 to=200>
    <cfset dateObject = dateAdd("d",x,now())>
    <cfoutput>#week(dateObject)# versus #ISOWeek(dateObject)#<br></cfoutput>
</cfloop>

Parameters:

Full UDF Source:

/**
 * Returns the weeknumber according to the ISO standard.
 * 
 * @param inputDate      Date object. (Required)
 * @return Returns a number. 
 * @author Ron Pasch (pasch@cistron.nl) 
 * @version 1, January 12, 2004 
 */
function ISOWeek(inputDate) {  
    var d = StructNew();
    var d2 = 0;
    var days = 0;
    d.yday = DayOfYear(inputDate);
    d.wday = DayOfWeek(inputDate)-1;
    d.year = Year(inputDate);
    days = d.yday - ((d.yday - d.wday + 382) MOD 7) + 3;
    if(days LT 0) {
        d.yday = d.yday + 365 + isLeapYear(d.year-1);
        days = d.yday - ((d.yday - d.wday + 382) MOD 7) + 3;
    } else {
        d.yday = (d.yday - 365) + isLeapYear(d.year);
        d2 = d.yday - ((d.yday - d.wday + 382) MOD 7) + 3;
        if (0 LTE d2) {
            days = d2;
        }
    }
    return int((days / 7) + 1);
}