OT: Requesting C advice

[Mike McCarty]

Les wrote:
> On Thu, 2007-05-24 at 17:07 -0500, Mike McCarty wrote:

[snip]
> 
>>
>>I suspect you are conflating "signed char" with "a character in the
>>execution environment which, when its code is stored into a signed char,
>>results in a negative value."
>>
>>Mike
>>-- 
>>p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
>>Oppose globalization and One World Governments like the UN.
>>This message made from 100% recycled bits.
>>You have found the bank of Larn.
>>I can explain it for you, but I can't understand it for you.
>>I speak only for myself, and I am unanimous in that!
>>
> 
> Hi, Mike,
>     when you passed the char to the printf using %d, it was promoted to
> an int which is signed.  That promotion will automatically extend the
> MSB, which in this case was a one (-1 decimal as a char is 0xff, and
> extended is 0xffffffff expressed as an int, which prints as -1.  

No, it does not automatically extend in the way you state.

$ cat uchar.c
#include <stdio.h>

int     main(void) {
     unsigned char   Chr;

     Chr = -1;
     printf("%d\n",Chr);
     return 0;
}

$ gcc -o uchar uchar.c
$ ./uchar
255

Just as I stated, you seem to be conflating the concept of
values and signedness of the type.

Mike
-- 
p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
Oppose globalization and One World Governments like the UN.
This message made from 100% recycled bits.
You have found the bank of Larn.
I can explain it for you, but I can't understand it for you.
I speak only for myself, and I am unanimous in that!