40. Date input routine
    ~~~~~~~~~~~~~~~~~~
This is a reasonably 'intelligent' Procedure for entering the date in a
program. It checks for sensible days, months and years, (1984 to 1999), takes
account of the different number of days in each month, and allows for Leap
Years. The original was written by a chap called Tim Davies, but I've altered
it a bit! You can enter the date in many forms, eg. 27.08.84 or 27-8-84 or
27/8/1984 or 27 8 84 or 27,08,84 and so on. The result is a string, date$,
which holds the date in the form 27-AUG-1984, and also three integer
variables, d%, m% and y%, which represent the day, month and year. If you do
not want the string date$, then change line 1070 to ENDPROC. If you do not
want to use the integer variables, then add them to the list of LOCAL
variables in line 1000. If you enter an invalid date, a beep will sound, and
you will be invited to try again. Note the use of INPUTLINE rather than
INPUT, in order to permit commas in the date.

   10 PROCdate:PRINT'"Todays Date is "date$'d%,m%,y%'
   20 GOTO10
 1000 DEFPROCdate:LOCALmx%,I%,d$,m$,y$:*FX21,0
 1010 PRINT:REPEAT:REPEATVDU127:UNTILPOS=0:INPUTLINE"Please submit
      date as DD.MM.YY "date$
 1020 d$=LEFT$(date$,2):IFASC(RIGHT$(d$,1))<48THENm$=MID$(date$,3,2)
      ELSEm$=MID$(date$,4,2)
 1030 y$=RIGHT$(date$,2):d%=VAL(d$):m%=VAL(m$):y%=VAL(y$)+1900
 1040 RESTORE1080:FORI%=1TOm%MOD13:READm$,mx%:NEXT
 1050 IFy%MOD4=0ANDm%=2THENmx%=29
 1060 VDU7:UNTILd%>0ANDd%<=mx%ANDm%>0ANDm%<13ANDy%>1983:*FX21,7
 1070 date$=STR$(d%)+"-"+m$+"-"+STR$(y%):ENDPROC
 1080 DATA JAN,31,FEB,28,MAR,31,APR,30,MAY,31,JUN,30,JUL,31,
      AUG,31,SEP,30,OCT,31,NOV,30,DEC,31