
Introduction
his book shows how to convert a given date to an absolute value representing the number
of days that have passed since 1 AD. This is useful when the difference of 2 dates has to
be calculated, e.g. to check if a timeout in days has been reached.


Get day number
his program is using a simple formula to determine the number of days. Every year has 365
days except for leapyears. In those year the February has 29 days. A year is a leapyear
if it can evenly be divided by 4 unless it can evenly be divided by 100 except it can
evenly be divided by 400. This means 2004 is a leapyear but 1900 was no leapyear and
again 2000 was a leapyear (because it can be divided by 400).
'Author : Daniel, Master Sourcerer at Kitana's Cas...
'Last change: March 3, 2004
'Email : sourcerer@kitana.org
#DIM ALL
'Returns the number of days a month has in a specific ...
'Input : M& = month (112)
' Y& = year
'Output: number of days in this month
FUNCTION MONTHDAYS&(M&,Y&)
LOCAL D&,Z$
Z$=CHR$(31,28,31,30,31,30,31,31,30,31,30,31)
D&=ASC(Z$,M&) 'assume default number of days
IF M&=2 THEN 'special handling for February
'29 days if year/4 unless year/100 except year/400
IF (Y& AND 3)=0 THEN
IF (Y& MOD 400)=0 OR (Y& MOD 100)<>0 THEN D&=29
END IF
END IF
MONTHDAYS&=D&
END FUNCTION
'Calculates how many days have passed from 1 AD to thi...
'Input : D& = day (131)

