signed and unsigned char

[Joseph Wakeling]

Hello all,

Is there any particular advantage or reason for always declaring a char
to be signed or unsigned?

Further, when compiling with gcc on Linux, I received warnings when
trying to sprintf an unsigned char *. I presume this is because in
Linux the default char type is signed. Is there any way to avoid the
error? Or should I not be using unsigned chars where the result would
be used with printf, sprintf, etc.?

Many thanks,

-- Joe

[Jordan Abel]

Re: signed and unsigned char

On 2005-12-14, Joseph Wakeling <joseph.wakelin g@gmail.com> wrote:[color=blue]
> Hello all,
>
> Is there any particular advantage or reason for always declaring a char
> to be signed or unsigned?
>
> Further, when compiling with gcc on Linux, I received warnings when
> trying to sprintf an unsigned char *. I presume this is because in
> Linux the default char type is signed. Is there any way to avoid the
> error? Or should I not be using unsigned chars where the result would
> be used with printf, sprintf, etc.?[/color]

In general, strings should just be char * - if you have an individual
char variable, pick signed or unsigned based on what you want it to be.
If you have a pointer that points at a block of bytes [some raw data for
something], it should be unsigned char *

[Joseph Wakeling]

Re: signed and unsigned char

Thanks very much! :-)

[Gerr]

Re: signed and unsigned char

> > Or should I not be using unsigned chars where the result would[color=blue][color=green]
> > be used with printf, sprintf, etc.?[/color]
>
> In general, strings should just be char * - if you have an individual
> char variable, pick signed or unsigned based on what you want it to be.
> If you have a pointer that points at a block of bytes [some raw data for
> something], it should be unsigned char *[/color]

What about strings using some extended character encoding, iso-8859-1
for example; are those to be considered as binary data (unsigned char
*) or regular
strings (char *) ? Is printf()'ing these strings legal ?

[Jordan Abel]

Re: signed and unsigned char

On 2005-12-14, Gerr <gertvierman@ho tmail.com> wrote:[color=blue][color=green][color=darkred]
>> > Or should I not be using unsigned chars where the result would
>> > be used with printf, sprintf, etc.?[/color]
>>
>> In general, strings should just be char * - if you have an individual
>> char variable, pick signed or unsigned based on what you want it to be.
>> If you have a pointer that points at a block of bytes [some raw data for
>> something], it should be unsigned char *[/color]
>
> What about strings using some extended character encoding, iso-8859-1
> for example; are those to be considered as binary data (unsigned char
> *) or regular
> strings (char *) ? Is printf()'ing these strings legal ?[/color]

read your implementation docs.

but consider that "strings" i.e. string literals have type char *.