Commodore VIC-20 - Page 149

Chapter 4: Advanced BASIC Programming 135
5 REM ROUTINE TO ACCEPT AND VERIFY A DATE
113 PRINT ":'111 !-III !-1Il !!!"CHRS( 13) ,; "1" ;
513 GOSUB 1eee:REM GET MONTH
613 IF CS=CHRS(13) OR CCS=CHRS(13) THEN 113
713 DTS=TCS: PRINT TAB(3)
813 REM CHECK FOR '.lAUD MONTH
913 M~=VAL <rCS)
95 IF M~(l OR M~)12 THEN 113
lee IF M%(l OR M~)12 THEN 113
1113 REM GET NUMBER OF DAYS IN MOt~TH
1213 D~=31
1313 IF t1%=2 THEN D~=2S
1413 IF M?=4 OR M:Y.=60R M~=9 OR M?=ll THEN D%=3e
1513 GOSUB 1131313: REM GET DAY
1613 IF CS=CHRs(13) OR CCS=CHRS(13) THEN 113
17aDT$=DT$+"-"+TCS: PRINT TAB(6)
1913 REM CHECK FOR VALID DAY
21313 IF IJAL<TCS)(l OR VAUTCS»])?' THEN 113
2113 GOSUB 1131313: REM GET YEAR
2213 DTS=DT$+"-"+TCS
2313 IF CS=CHRS(13) OR CCS=CHRS(13) THEN 113
2413 REM CHECK FOR VALID YEAR
2713 STOP
1131313 REM TWO CHARACTER INPUT SUBROUTINE
laHl GET CS: IF CS="" THEN 113113
11311 IFVAUBS»laa THEN PRINT"T"
11315 IF CS=CHRS(13) THEN 113513
11316 IF Cs{"a" OR CS)"9" THEN lela
113213 PRINT CS;
113313 GET CCS: IF CCS=" II THEN 113313
11335' IF CCS=CHRS(13) THEN 113513
11336 IF CCs("a" OR CCS)"9" THEN 113313
113413 PRINT CCS;
113513 TCS=CS+CCS
113613 RETURN
FIGURE 4·1. Simple program to enter and verify a date