Functions
Returns the number of days in a month, taking leap years into account.
Returns the number of weeks in the year, where weeks are taken to start on Monday. Will be 52 or 53. The date must be valid. (Years always have 52 7-day periods, plus 1 or 2 extra days depending on whether it's a leap year. This function is basically telling you how many Mondays are in the year, i.e. there are 53 Mondays if one of the extra days happens to be a Monday.)
Returns the number of weeks in the year, where weeks are taken to start on Sunday. Will be 52 or 53. The date must be valid. (Years always have 52 7-day periods, plus 1 or 2 extra days depending on whether it's a leap year. This function is basically telling you how many Sundays are in the year, i.e. there are 53 Sundays if one of the extra days happens to be a Sunday.)
Returns true if the year is a leap year.
Returns true if the Julian day is valid. Anything greater than zero is basically a valid Julian, though there is a 32-bit limit.
Returns true if the month value is valid. The 12 #GDateMonth enumeration values are the only valid months.
Returns true if the weekday is valid. The seven #GDateWeekday enumeration values are the only valid weekdays.