In message: <[EMAIL PROTECTED]>
Andreas Schwab <[EMAIL PROTECTED]> writes:
: Johannes Schindelin <[EMAIL PROTECTED]> writes:
:
: > It has been a really long time I have been working on a broken system that
: > did not default to "signed".
:
: The only thing that is broken is your knowlege of C.
gcc on ARM systems default to unsigned. The C standard specifically
states that char is either signed or unsigned at the whim of the
implementor:
Section 6.2.5 para 15:
[#15] The three types char, signed char, and unsigned char
are collectively called the character types. The
implementation shall define char to have the same range,
representation, and behavior as either signed char or
unsigned char.30)
...
30)CHAR_MIN, defined in <limits.h>, will have one of the
values 0 or SCHAR_MIN, and this can be used to
distinguish the two options. Irrespective of the choice
made, char is a separate type from the other two and is
not compatible with either.
...
I just confirmed that gcc on arm does indeed default to unsigned
chars:
% cat xxx.c
signed char cs = -1;
unsigned char cu = -1;
char c = -1;
void foo()
{
int i = 0;
if (cs < 0) i++;
if (cu < 0) i++;
if (c < 0) i++;
}
% gcc -v
Using built-in specs.
Configured with: FreeBSD/arm system compiler
Thread model: posix
gcc version 3.4.4 [FreeBSD] 20050518
% gcc -W -c xxx.c
xxx.c: In function `foo':
xxx.c:9: warning: comparison is always false due to limited range of data type
xxx.c:10: warning: comparison is always false due to limited range of data type
%
Note: line 10 is the naked char.
Warner
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