nthWeekDay — Date

Returns the date of the nth weekday within the specified month and year.

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Interface

#include <codecogs/units/date/nthweekday.h>

using namespace Units::Date;

int nthWeekDay(int Nth, int WeekDay, int Year, int Month, int Type=1)

Calculates the date of the nth occurrence of a particular weekday (Sunday to Saturday) within a specified month and year. Many public holidays and other events (see also summertime) are performed on specific days of the week; very often the first or last occurrence of that day within the month. This function uses weekdays within the Gregorian calendar to return the serial Julian date (number of days since 24 November 4714BC).

For example, US events include:

Martin Luther King Day, third Monday in January
President's Day, third Monday in February
Armed Forces Day, third Saturday in May
Mother's Day, second Sunday in May
Memorial Day, last Monday in May
Father's Day, third Sunday in June
Labor Day, first Monday in September
Columbus Day, second Monday in October
Thanksgiving Day, fourth Thursday in November

UK holidays include:

May Day Bank Holiday, first Monday in May
Spring Bank Holiday, last Monday in May
Late Summer Holiday, last Monday in August

Example 1

To compute the UK holidays:

#include <stdio.h>
#include <codecogs/units/date/nthweekday.h>
#include <codecogs/units/date/dateymd.h>
#include <codecogs/units/date/month_str.h>
using namespace Units::Date;

int main()
{
  int d,m,y;
  for(int i=2004; i<=2006; i++)
  {
    printf("\nIn %d:",i);
    dateYMD(nthWeekDay(1, Monday, i, May), y,m,d);        // First Monday
    printf("\n   May Day Bank Holiday is on: %2d %s",d,month_str(m));

    dateYMD(nthWeekDay(0, Monday, i, May), y,m,d);        // last Monday
    printf("\n   Spring Bank Holiday is on:  %2d %s",d,month_str(m));

    dateYMD(nthWeekDay(0, Monday, i, August), y,m,d);     // last Monday
    printf("\n   Late Summer Holiday is on:  %2d %s",d,month_str(m));
  }
  return 0;
}

Output:

In 2004:
May Day Bank Holiday is on:  3 May
Spring Bank Holiday is on:  31 May
Late Summer Holiday is on:  30 August
In 2005:
May Day Bank Holiday is on:  2 May
Spring Bank Holiday is on:  30 May
Late Summer Holiday is on:  29 August
In 2006:
May Day Bank Holiday is on:  1 May
Spring Bank Holiday is on:  29 May
Late Summer Holiday is on:  28 August

Parameters

Nth

identifies which WeekDay from the start of the month to obtain (e.g. the 1st Friday, 3rd Monday). A zero value will return the date of the last WeekDay, with negative values returning earlier weekdays from the end of the month.

WeekDay

is the day of the week required, with its value depending upon the Type (see below).

Year

can be any integer greater than 4800 BC (-4799).

Month

contains the month of the year. This value must be within the range -9 to 14 (inclusive), though values outside the range 1-12 will be divided by 12, such that the Year is incremented by the quotient and the Month set to the remainder.

Type

defines the input form for the WeekDay:

Blank

Type=1 : WeekDay contains numbers 1 (Sunday) through 7 (Saturday) - default behaviour of Microsoft Excel.
Type=2 : WeekDay contains numbers 1 (Monday) through 7 (Sunday).
Type=3 : WeekDay contains numbers 0 (Monday) through 6 (Sunday).

Interactive Calculator

Nth

WeekDay

Year

Month

Type

Result –