fgetc() returns an int so that EOF may be distinguished from valid
return values. Valid values are 8-bit values. EOF is a 32-bit value.
EOF is a 32-bit two's-complement -1 (0xffffffff), and -1 input is 8-bit
two's-complement -1 (0xff). When fgetc() casts this to an int, it
becomes 0x000000ff, or 255, and thus the two values may be distinguished
from each other.
I haven't looked at your code, but you are probably comparing EOF with
the value returned by fgetc() after it has been cast to a char. EOF is
getting cast to a char implicitly in the comparison, so the comparison
becomes a comparison between 0xff and 0xff. You need to test the int
returned by fgetc() for EOF before assigning it to a char.
Gábor Kövesdán wrote:
Hello,
I have a problem when reading files with fgetc when a 0xff character
comes. In my code the reading stops at that point as if EOF had been
reached, but that's not actually the case.
The code is here:
http://p4web.freebsd.org/@md=d&cd=//&c=Nsd@//depot/projects/soc2008/gabor_textproc/grep/file.c?ac=64&rev1=40
And the problem occurs in grep_fgetln() when the buffers is being filled
in:
for (; i < bufsiz && !grep_feof(f); i++)
binbuf[i] = grep_fgetc(f);
Thanks in advance,
--
James Bailie <[email protected]>
http://www.mammothcheese.ca
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