CFLib.org – Common Function Library Project

Description:
Returns the day of the month(1-31) of an Nth Occurrence of a day (1-sunday,2-monday etc.)in a given month. Used to determine holidays and special events that occur on the nth occurrence of a day in a month.

Return Values:
Returns a numeric value.

Example:

<CFOUTPUT>
The third Sunday in August of 2001 is on August
#GetNthOccOfDayInMonth(3,1,8,2001)#.
</CFOUTPUT>

Parameters:

Full UDF Source:

/**
 * Returns the day of the month(1-31) of an Nth Occurrence of a day (1-sunday,2-monday etc.)in a given month.
 * 
 * @param NthOccurrence      A number representing the nth occurrence.1-5. 
 * @param TheDayOfWeek      A number representing the day of the week (1=Sunday, 2=Monday, etc.). 
 * @param TheMonth      A number representing the Month (1=January, 2=February, etc.). 
 * @param TheYear      The year. 
 * @return Returns a numeric value. 
 * @author Ken McCafferty (mccjdk@yahoo.com) 
 * @version 1, August 28, 2001 
 */
function GetNthOccOfDayInMonth(NthOccurrence,TheDayOfWeek,TheMonth,TheYear)
{
  Var TheDayInMonth=0;
  if(TheDayOfWeek lt DayOfWeek(CreateDate(TheYear,TheMonth,1))){
    TheDayInMonth= 1 + NthOccurrence*7  + (TheDayOfWeek - DayOfWeek(CreateDate(TheYear,TheMonth,1))) MOD 7;
  }
  else{
    TheDayInMonth= 1 + (NthOccurrence-1)*7  + (TheDayOfWeek - DayOfWeek(CreateDate(TheYear,TheMonth,1))) MOD 7;
  }
  //If the result is greater than days in month or less than 1, return -1
  if(TheDayInMonth gt DaysInMonth(CreateDate(TheYear,TheMonth,1)) OR   TheDayInMonth lt 1){
    return -1;
  }
  else{
    return TheDayInMonth;
  }
}