🚀 go-pugleaf

On Thu, 13 Nov 1997, Karol Wojtiuk wrote:

> funkcja isdigit jest zadeklarowana następująco:
[...]

W Linuxowym GCC:

ISALPHA(3)          Linux Programmer's Manual          ISALPHA(3)

NAME
       isalnum,  isalpha,  isascii,  isblank,  iscntrl,  isdigit,
       isgraph,  islower,  isprint,  ispunct,  isspace,  isupper,
       isxdigit - character classification routines

[...]

DESCRIPTION
       These functions check whether c, which must have the value
       of an unsigned char or EOF, falls into a certain character
       class according to the current locale.

[...]

CONFORMING TO
       ANSI  -  C,  BSD 4.3.  isascii() is a BSD extension and is
       also an SVID extension.  isblank() is a GNU extension.

Tak więc tutaj jest jasno określone, że znaki przyjmować wartości 0..255
albo EOF.

W pliku include/ctype.h można przeczytać:

/* These are defined in ctype-info.c.
   The declarations here must match those in localeinfo.h.

   These point into arrays of 384, so they can be indexed by any `unsigned
   char' value [0,255]; by EOF (-1); or by any `signed char' value
   [-128,-1).  ANSI requires that the ctype functions work for `unsigned
   char' values and for EOF; we also support negative `signed char' values
   for broken old programs.  The case conversion arrays are of `int's
   rather than `unsigned char's because tolower (EOF) must be EOF, which
   doesn't fit into an `unsigned char'.  */

                                QRCZAK
    __("<             Marcin Kowalczyk
    \__/             qrczak@knm.org.pl
     ^^      http://kki.net.pl/qrczak/