Calculate the number of weeks a year has. The first parameter is the year for which the number of weeks must be determined.
This predicate is located in the file 'datetime.txt', use ensure_loaded/1 to include this file.
see also: age/7 day_number/4 day_of_week/2 datetime module decode_date/4 decode_datetime/7 decode_time/4 encode_date/4 encode_datetime/7 encode_time/2 encode_time/3 encode_time/4 ensure_loaded/1 leap_year/1 length_month/3 monday_of_week/3 monday_of_week/5 reverse_day_number/4 start_of_week/3
| Example | |
| num_weeks_in_year(1998, Num). | succeeds, Num = 53 |
| num_weeks_in_year(1999, Num). | succeeds, Num = 52 |
| num_weeks_in_year(1998, 52). | fails, because 1998 has 53 weeks |
| Exceptions | |
| The Year parameter is not an integer | a type_error(evaluable, Value) exception is thrown, Value is unified with the incorrect argument |