problem in K&R answer book

[Prem Mallappa]

Hi everyone
this is the program given in answer book to K&R

=============== =============== ======
#include <stdio.h>

int main()
{
printf (" signed char = %d", -(char) ((unsigned char) ~0 >> 1));
printf (" signed char = %d", (char) ((unsigned char) ~0 >> 1));
return 0;
}

=============== =============== ====
This is to print the maximum value we can store in a signed char..
the output of this is
-127
127
but we can store -128 as the value in a signed char and also in <limits.h>

# define SCHAR_MIN (-128)

why is it given in that way in the most famous K&R answerbook
am i wrong or the program is wrong..
plz help me
regards
prem

[Dan Pop]

In <63************ **************@ posting.google. com> ai***@acay.com. au (Peter Nilsson) writes:

Integer conversion is specifically implementation defined in C90 when
the value cannot be represented in the target type. Only C99 allows
the potential for an implementation defined signal to be raised if the
value cannot be represented.

[I have no idea why C99 added this 'feature'.]

To fix something that wasn't broken in the first place. And to break
perfectly correct and portable C90 code that relied on this feature.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de