39. Input with timeout
    ~~~~~~~~~~~~~~~~~~
In some applications, especially Educational programs, it is useful to have
an input routine which "times-out" if no key is pressed for a certain number
of seconds. This is possible for single-character routines like INKEY, but
not with INPUT. This Function solves the problem, and also enables you to set
limits on the string size. You must pass the minimum and maximum lengths
allowed, and also the number of seconds for timeout after the last key was
pressed. If the routine times-out before you press <Return>, then it will act
as if it had pressed <Return> for you. If, however, you would rather that it
returned the null, (or empty), string instead, then see the REM statement.
The example in line 10 allows a minimum of 1 character, and maximum of 12,
with a 5-second timeout. You may omit all spaces in the listing, if you wish,
except those inside quotes. Thanks to Brian Parker G6JPZ for suggesting the
idea, which has been incorporated into the routine given in the Golden Oldie
Tip #11.

  10 PRINT"Enter name ? ";:A$=FNinp(1,12,5):PRINT A$':GOTO 10
  20 :
 100 DEFFNinp(min%,max%,secs%):LOCAL G%,G$,GI$:*FX15,1
 110 TIME=0:PRINT G$;
 120 G$=INKEY$(0):G%=ASC(G$)
 130 IF TIME>secs%*100 THEN PRINT:VDU7:=GI$ ELSE IF G%=-1 THEN 120
 140 REM Alter the =GI$ in line 130 to ="" if string is to be null on
     timeout
 150 IF (LEN(GI$)=max% AND G%<>13 AND G%<>127) OR (((LEN(GI$)=0 AND
     (G%<33 OR G%>126)) OR (LEN(GI$)<min% AND G%=13)) AND (min%>0 OR
     G%<>13)) THEN VDU7:GOTO 120
 160 IF G%>31 AND G%<127 THEN GI$=GI$+G$:GOTO 110 ELSE IF G%=127 THEN
     GI$=LEFT$(GI$,LEN(GI$)-1):GOTO 110 ELSE IF G%<>13 THEN VDU7:
     GOTO 120 ELSE PRINT:=GI$