The first week of the month is week 0 - the week that has the first day of the month.
The last week is the week with the last day of the month
Hence the weeknumber of the last week of july IS THE SAME as the weeknumber of the first week of august
** UNLESS **
the month in question ends on the last day of the last week, in wich case the following month would start on the first day of the new week and have a different weeknumber
:)
