On Fri, Mar 27, 2009 at 4:31 PM, Graham Davies <ecros...@ecrostech.com>wrote:

>  David VanHorn wrote:
> "Ok, so that leaves me VERY confused."
> Maybe it would help to think about logic levels in simulation.  The three
> basic levels are "low", "high" and "unknown".  The three variations of the
> char type are similar, signed, unsigned and unspecified.  I think that the
> reason the unspecified variant of char got into the C language definition
> was political, not technical.  The other basic integer types don't share
> this quirk.
>

Right, the unspecified variant looks like a disaster waiting to happen,
IMHO.


>  The compiler is probably warning you because a signed char and an
> unsigned char are both different from an unspecified or plain char, just
> like low and high are different from unknown.
>

Ok, but using the portable types, there does not appear to be an unspecified
char, which seems like a very good idea to me.


>  The reason that a function would take a char of unspecified signedness is
> that the writer of the function reasons that only the least significant
> seven bits mean anything, so why bother with what the MSB does.  I think
> it's kind-of traditional that 7-bit ASCII is represented as a plain char.
> Personally, I use uint8_t.
>

Right, and that's what makes the most sense to me, ASCII is unsigned, so
unsigned char should be right, but the routine apparently requires signed!
Previously, I was using the "unsigned char" and "signed char" forms, and the
"unsigned char" form gave me warnings.. So I used "signed char", which
satisfied the compiler...

Now I'm in the situation where I can't seem to satisfy it with signed or
unsigned, in the "uint8_t" and "int_t" forms.

I don't want to cast aspersions, but it seems to me like lcd_puts is buggy,
if it's requiring sign.



>  Graham.
>
>
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-- 
David VanHorn
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