How to write a text input routine in Commodore BASIC

Jay's Commodore Podcast

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6+ y ago 22:52

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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:

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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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