In this screencast I’ll show you how to write your own INPUT routine in Commodore BASIC. This comes in handy when you want to reject certain keys from being used when asking users for keyboard input. In my example I’m going to allow all alpha characters (A-Z), as well as SPACE, RETURN and the DELETE key.
Here’s the code:
.gist table { margin-bottom: 0; }













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5 print



10 w$=""



20 print "(greater than)_";



30 get a$:if a$="" then 30



40 a=asc(a$)



50 if a=13 then 200:rem return



60 if a=32 then 110:rem space



70 if a=20 then 300:rem backspace



100 if a<65 or a>90 then 30



110 print chr$(20);a$;"D";



115 w$=w$+a$



120 goto 30



200 rem handle return



210 print chr$(20)



215 if w$="" then print:print"you typed



nothing!":end



220 print:print"you typed:":print w$



230 end



300 rem handle backspace



305 if len(w$)=0 then 30



310 print chr$(20);chr$(20);"D";



320 w$=left$(w$,len(w$)-1)



330 goto 30






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input.bas

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