John Darrington <[email protected]> writes:
> On Sat, Sep 25, 2010 at 12:23:48PM -0700, Ben Pfaff wrote:
> libunistring uses uint8_t (unsigned char) for UTF-8. That's the
> same as what PSPP uses currently for "union value". I'm inclined
> to do this:
>
> * Use uint8_t for UTF-8, via libunistring.
>
> * Use char for multibyte strings in the current locale.
>
> * Change "union value" to use signed char, in place of
> its current use of unsigned char.
>
> Then we'll be able to cleanly distinguish each of these types
> (char vs. unsigned char vs. signed char) and get some help from
> the compiler.
>
> How is "char" different from "signed char" ? The compiler automatically
> assumes a type is signed if no qualifier is specified.
"char" is special. There are three distinct character types:
char, signed char, and unsigned char. As a demo, compile this:
int foo(void)
{
char c;
signed char sc;
unsigned char uc;
&c == ≻
&c == &uc;
&sc == &uc;
}
and you'll get these warnings:
tmp.c: In function ‘foo’:
tmp.c:6: warning: comparison of distinct pointer types lacks a cast
tmp.c:6: warning: statement with no effect
tmp.c:7: warning: comparison of distinct pointer types lacks a cast
tmp.c:7: warning: statement with no effect
tmp.c:8: warning: comparison of distinct pointer types lacks a cast
tmp.c:8: warning: statement with no effect
tmp.c:9: warning: control reaches end of non-void function
> Also, the Gtk/Glib functions use plain char for UTF8 strings,
> so we would need a lot of casts between the two in the gui
> code. If libuistring has decided to use the convention the
> other way around, that is unfortunate.
Hmm.
--
Ben Pfaff
http://benpfaff.org
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