In previous articles I have demonstrated how to find the date of the first instance of a weekday in a month, and how to number the weeks in a month and find what week number a particular date falls on.
These combined with the built in ColdFusion's built in date functions cover most situations you could encounter when doing reports based on weeks numbers. However sometimes it is necessary to base a week number off the date off the first instance of a weekday in the month.
For example using the previous method of week numbering, if the first day of the month fell on a Saturday then the first week in the month would be a single day as the next day Sunday would be the start of a new week. However in reality you might want the week numbering to be based off the first business day in the month (Monday).
So how do we do this. Well this is a little function I wrote recently to solve exactly this problem.
To accomplish this I simply used the previous calculations to find the normal week numbering system plus the first instance of the desired base day Monday and if the first Monday is in week 2 shift the week numbering by 1 position to compensate. I know simple right.