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Forum Index : Microcontroller and PC projects : bug in LEFT$, RIGHT$ & MID$

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BobDevries

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Joined: 08/06/2011
Location: Australia
Posts: 266

Posted: 01:49am 31 Aug 2011

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Hi all,

I just now found a bug in the LEFT$() and RIGHT$() and MID$() functions.

Try this:

PRINT LEFT$("hello",1)
PRINT RIGHT$("hello",1)
PRINT MID$("hello,3,1)

Notice that it prints a white block beside the correct output?

Regards,

Bob Devries
Dalby, QLD, Australia

BobDevries

Senior Member

Joined: 08/06/2011
Location: Australia
Posts: 266

Posted: 01:59am 31 Aug 2011

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Hi all,

just another observation...

the line:

PRINT MID$("hello",3,2)

works as expected; no white block. So it seems to be only on single-character output?

Regards,

Bob Devries
Dalby, QLD, Australia

BobDevries

Senior Member

Joined: 08/06/2011
Location: Australia
Posts: 266

Posted: 02:09am 31 Aug 2011

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Me again :)

It appears that it's sort-of my mistake... I'll explain....

I often run my analog clock programme, and it has a white border about 2 characters wide. If I ESCAPE out of it, the border is left on the screen. Then when a single character is printed, what's left of the border is immediately behind the character on the screen.

Now, IMHO, the print routine *should* clear to the end of the line *unless* a semi-colon is appended to the command.

so,

PRINT "L"

should clear the screen line to the right, and

PRINT "L";

should not.

comments?

Regards,

Bob Devries
Dalby, QLD, Australia

aargee
Senior Member

Joined: 21/08/2008
Location: Australia
Posts: 255

Posted: 05:41am 31 Aug 2011

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Bob,

I think from memory, that most Basics did not clear to the end of the line. I clearly remember having to do a CLS if I wanted a clean slate to work on, now whether it should be implemented in MM Basic, that maybe one for the wish list.

For crying out loud, all I wanted to do was flash this blasted LED.

BobDevries

Senior Member

Joined: 08/06/2011
Location: Australia
Posts: 266

Posted: 05:58am 31 Aug 2011

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Hi aargee,

Well, I was comparing against my Tandy Colour Computer 3, which definitely does clear the rest of the line unless the print is terminated with a semi-colon.

Regards,

Bob Devries
Dalby, QLD, Australia

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