Excel's Formula - sisman

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Part VI: Developing Custom Worksheet Functions
Date Functions
Chapter 6 presents a number of useful Excel functions and formulas for calculating dates, times,
and time periods by manipulating date and time serial values. This section presents additional
functions that deal with dates.
The companion CD-ROM contains a workbook, date functions.xlsm, that demonstrates
the functions presented in this section.
Calculating the next Monday
The following NEXTMONDAY function accepts a date argument and returns the date of the following
Monday:
Function NEXTMONDAY(d As Date) As Date
NEXTMONDAY = d + 8 – WeekDay(d, vbMonday)
End Function
This function uses the VBA WeekDay function, which returns an integer that represents the day
of the week for a date (1 = Sunday, 2 = Monday, and so on). It also uses a predefined constant,
vbMonday.
The following formula returns 12/27/2010, which is the first Monday after Christmas Day, 2010
(which is a Saturday):
=NEXTMONDAY(DATE(2010,12,25))
The function returns a date serial number. You will need to change the number format
of the cell to display this serial number as an actual date.
If the argument passed to the NEXTMONDAY function is a Monday, the function returns the following
Monday. If you prefer the function to return the same Monday, use this modified version:
Function NEXTMONDAY2(d As Date) As Date
If WeekDay(d) = vbMonday Then
NEXTMONDAY2 = d
Else
NEXTMONDAY2 = d + 8 – WeekDay(d, vbMonday)
End If
End Function