note 49457 modified in function.date by danbrown

Calculus of weeks in a year. Since there is date("W") many still seem to have a problem regarding how many weeks there are in an year. Some rather complex solutions have been shown here. It's defined, that a week which begins in december and ends in january the following year belongs to the year where most of its days lie. Therefore a week with at least 4 days in december is the last week of that year and a week with at least 4 days in january is the first week in the new year. This concludes, that the last week of a year always contains the 28th day of december. So if you take date("W") on that day of a given year you always get the correct number of weeks for that year. The other end of that definition is that the 4th day of january always lies in the first week of a year. I hope this solves a lot of confusion. (For those asking what all this fuzz about counting weeks is about: normally theres 52 weeks in a year but sometimes its 53 weeks in a year) I wrote it down as a function, but as this is rather trivial one might consider using the date(...) only. <?php function weeks($year) { return date("W",mktime(0,0,0,12,28,$year)); } ?> --was-- Calculus of weeks in a year. Since there is date("W") many still seem to have a problem regarding how many weeks there are in an year. Some rather complex solutions have been shown here. It's defined, that a week which begins in december and ends in january the following year belongs to the year where most of its days lie. Therefore a week with at least 4 days in december is the last week of that year and a week with at least 4 days in january is the first week in the new year. This concludes, that the last week of a year always contains the 28th day of december. So if you take date("W") on that day of a given year you always get the correct number of weeks for that year. The other end of that definition is that the 4th day of january always lies in the first week of a year. I hope this solves a lot of confusion. (For those asking what all this fuzz about counting weeks is about: normally theres 52 weeks in a year but sometimes its 53 weeks in a year) I wrote it down as a function, but as this is rather trivial one might consider using the date(...) only. function weeks($year) { return date("W",mktime(0,0,0,12,28,$year)); } http://php.net/manual/en/function.date.php