'********************************************
'* Compute number of days between two dates *
'* ---------------------------------------- *
'* Ref.: "Mathématiques par l'informatique  *
'*        individuelle (1) par H. Lehning   *
'*        et D. Jakubowicz, Masson, Paris,  *
'*        1982" [BIBLI 06].                 *
'********************************************
' Note: The two dates must be between 01/01/1901
'       and 12/31/2099 to avoid treatment of special
'       "secular" years, such as 1800, 1900, 2100...
'       (2000, a multiple of 400, is a normal year!)
'
' The first date is M, D, Y
' N, number of days between first date and fictitious
' starting date 01/00/1901, is given by formula:
'
'       N = INT(365,25*(Y-1901)+A(M)+D)
'
' where A(M) is given by table below:
'
' M    1  2  3     4      5      6      7      8      9     10     11     12
' A(M) 0 31 59,25 90,25 120,25 151,25 181,25 212,25 243,25 273,25 304,25 334,25
'
'       First N is saved in R.
'
' The second date is again M, D, Y
' N is again computed with same formula.
'
' Final result is R - N.
'**************************************************
DIM A(12)
A(1) = 0: A(2) = 31: A(3) = 59.25: A(4) = 90.25: A(5) = 120.25: A(6) = 151.25
A(7) = 181.25: A(8) = 212.25: A(9) = 243.25: A(10) = 273.25: A(11) = 304.25: A(12) = 334.25
10 CLS
PRINT
PRINT " Compute number of days between two dates"
PRINT "     (from 01/01/1901 to 12/31/2099)"
PRINT
PRINT " Enter first date (M,D,Y): ";
GOSUB 1000
R = N
PRINT " Enter second date (M,D,Y): ";
GOSUB 1000
R = N - R
PRINT
PRINT " Number of days: "; R
PRINT
END

1000 INPUT "", M, D, Y
N = 365.25 * (Y - 1901) + A(M) + D
N = INT(N)
RETURN

'end of file ndays.bas