25 Years of Programming
An open source source for C, C++, OWL, BASIC, MDB, XLS, DOT, and more...

Home Projects Up Sitemap Search Blog Forum+Chat About Us Privacy Terms of Use Feedback FAQ Images Services Payments Humor Music

Language translation
by Google is available
when JavaScript enabled.
Google Translate
is an alternative.

Calculate number of days between dates, Microsoft MBASIC program

The NUMDAYS.BAS program written for the Heathkit H-89 computer in Microsoft MBASIC calculates the number of days between two dates.

It is useful for financial calculations such as those involving interest payments or accruals, and in calculations to determine fair stock, bond, or stock option prices. The data are also used sometimes when attempting to predict likely future prices for those financial instruments.

On the H-89, each year takes about 13 seconds to calculate.

NUMDAYS.BAS

10 REM PROGRAM 'NUMDAYS.BAS'
20 REM COPYRIGHT (C)1982, 2001 STEVEN WHITNEY.  
21 REM Initially published by http://25yearsofprogramming.com.
22 REM Published under GNU GPL (General Public License) Version 3, with ABSOLUTELY NO WARRANTY.
30 DATA 31,28,31,30,31,30,31,31,30,31,30,31
40 DEFINT A-S, U-Z: DEFDBL T
45 CLS
50 PRINT STRING$(75, "="): PRINT , "*** NUMBER OF DAYS BETWEEN TWO DATES ***": PRINT
60 PRINT , "PLEASE SEPARATE DATE COMPONENTS BY COMMAS :"
70 PRINT , SPC(3); "JANUARY 10, 1982 ==>  1,10,1982"
80 PRINT STRING$(75, "-"): PRINT
90 PRINT , , "ENTER START DATE 0,0,0, TO STOP PROGRAM"
100 PRINT
110 N = 0
120 INPUT "STARTING DATE (MONTH,DAY,YEAR): "; B, C, A
130 IF B = 0 AND C = 0 AND A = 0 THEN END
140 IF B < 1 OR B > 12 OR C < 1 OR (B = 2 AND C > 29) OR ((B = 4 OR B = 6 OR B = 9 OR B = 11) AND C > 30) OR C > 31 THEN PRINT , "IMPOSSIBLE": GOTO 120
150 IF (A / 100 = INT(A / 100) AND A / 400 = INT(A / 400) AND B = 2 AND C > 29) OR (A / 100 = INT(A / 100) AND A / 400 <> INT(A / 400) AND B = 2 AND C > 28) THEN PRINT , "IMPOSSIBLE": GOTO 120
160 INPUT "  ENDING DATE (MONTH,DAY,YEAR): "; F, G, E
170 IF F < 1 OR F > 12 OR G < 1 OR (F = 2 AND G > 29) OR ((F = 4 OR F = 6 OR F = 9 OR F = 11) AND G > 30) OR G > 31 THEN PRINT , "IMPOSSIBLE": GOTO 160
180 IF (E / 100 = INT(E / 100) AND E / 400 = INT(E / 400) AND F = 2 AND G > 29) OR (E / 100 = INT(E / 100) AND E / 400 <> INT(E / 400) AND F = 2 AND G > 28) THEN PRINT , "IMPOSSIBLE": GOTO 160
190 B$ = STR$(B): IF LEN(B$) < 3 THEN B$ = "0" + RIGHT$(B$, 1)
200 C$ = STR$(C): IF LEN(C$) < 3 THEN C$ = "0" + RIGHT$(C$, 1)
210 F$ = STR$(F): IF LEN(F$) < 3 THEN F$ = "0" + RIGHT$(F$, 1)
220 G$ = STR$(G): IF LEN(G$) < 3 THEN G$ = "0" + RIGHT$(G$, 1)
230 T1 = VAL(STR$(A) + B$ + C$): REM START DATE
240 T2 = VAL(STR$(E) + F$ + G$): REM END DATE
250 IF T2 < T1 THEN PRINT : PRINT "END DATE IS PRIOR TO START DATE - START FROM BEGINNING": PRINT STRING$(75, "="): GOTO 90
260 GOTO 330
270 C = C + 1
280 N = N + 1
290 IF C > D THEN B = B + 1: C = 1: K = 1
300 IF B > 12 THEN A = A + 1: B = 1: D = 31: K = 0
310 IF A = E AND B = F AND C = G THEN 380
320 IF K = 0 THEN 370
330 RESTORE
340 FOR I = 1 TO B: READ D: NEXT I
350 IF A / 4 = INT(A / 4) AND B = 2 THEN D = 29: IF A / 100 = INT(A / 100) THEN D = 28: IF A / 400 = INT(A / 400) THEN D = 29
360 K = 0
370 GOTO 270
380 PRINT : PRINT , "DIFFERENCE IS", N; "DAYS.": GOTO 80
390 REM COPYRIGHT (C)1982 STEVEN WHITNEY.