[hobbit] Ton of "differ in signedness" warnings?

[TJ Yang]

I really  don't like to  ignore the warning message from compiler.
so I am spending some effort (R2) on subject of gcc compilation warning message.
Hope to get rid all of them.

Fist challenge is "unsigned char" usage,

The question is  why Henrik decided to use "unsigned char" on
strings,array in hobbit source code ?
According  R1 book,

unsigned character is 1 byte long and value range to be 0 to 2^8 -1.
signed  character  is 1 byte long   and value range is  -2^7 to 2^7-1.

both signed and unsigned char are all 1 byte long, so saving space is
not a motive.

Is the intention of declaring unsigned char is to disallow minus
value(non-ASCII) in a character ?


R1: C a software engineering approach by Peter A. Darneil.
R2: http://en.wikibooks.org/wiki/System_Monitoring_with_Xymon/Developer_Guide#Compilation_Errors_and_Warning
R3: following two example diffs are illustration of places in src
using unsigned char.
<snip>
Index: client/clientupdate.c
===================================================================
--- client/clientupdate.c       (revision 6219)
+++ client/clientupdate.c       (working copy)
@@ -96,7 +96,7 @@
                        char tmpfn[PATH_MAX];
                        char *srcfn;
                        FILE *tmpfd, *srcfd;
-                       unsigned char buf[8192];
+                       char buf[8192];
                        long n;
                        struct stat st;
                        int cperr;
Index: client/logfetch.c
===================================================================
--- client/logfetch.c   (revision 6219)
+++ client/logfetch.c   (working copy)
@@ -431,7 +431,7 @@
        static char *result = NULL;
        digestctx_t *ctx;
        FILE *fd;
-       unsigned char buf[8192];
+       char buf[8192];
        int openerr, buflen;

         if ((ctx = digest_init(dtype)) == NULL) return "";
[tjyang at f12 4.3.0]$


On Wed, Feb 17, 2010 at 11:45 AM, Malcolm Hunter
<malcolm.hunter at gmx.co.uk> wrote:
>> Why is there something like this:
>>
>> unsigned char *message;
>>
>> or
>> static unsigned char *cause = NULL;
>>
>> I am guessing these are strings - so why the unsigned?
>
> This thread may help explain:
>
> http://bytes.com/topic/c/answers/61480-why-use-unsigned-char-ever
>
> Malcolm
>
>
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-- 
T.J. Yang