ctype.h
The standard functions that work with characters are in the
ctype.h interface.
man ctype
<![CDATA[
CTYPE(3C) Silicon Graphics CTYPE(3C)
NAME
isdigit, isxdigit, islower, isupper, isalpha,
isalnum, isspace, iscntrl, ispunct, isprint,
isgraph, isascii, tolower, toupper, toascii,
_tolower, _toupper, setchrclass - character
handling
SYNOPSIS
#include <ctype.h>
int isdigit (int c);
int isxdigit (int c);
int islower (int c);
int isupper (int c);
int isalpha (int c);
int isalnum (int c);
int isspace (int c);
int iscntrl (int c);
int ispunct (int c);
int isprint (int c);
int isgraph (int c);
int isascii (int c);
int tolower (int c);
int toupper (int c);
int toascii (int c);
int _tolower (int c);
int _toupper (int c);
int setchrclass (char *chrclass);
DESCRIPTION
The character classification macros listed below
return nonzero for true, zero for false. isascii
is defined on all integer values; the rest are
defined on valid members of the character set and
on the single value EOF
[see stdio(3S)] (guaranteed not to be a character
set member).
isdigit tests for the digits 0 through 9.
isxdigit tests for any character for which
isdigit is true or for the letters a
through f or A through F.
islower tests for any lowercase letter as
defined by the character set.
isupper tests for any uppercase letter as
defined by the character set.
isalpha tests for any character for which
islower or isupper is true and
possibly any others as defined
by the character set.
isalnum tests for any character for which
isalpha or isdigit is true.
isspace tests for a space, horizontal-tab,
carriage return, newline,
vertical-tab, or form-feed.
iscntrl tests for ``control characters''
as defined by the character set.
ispunct tests for any character other than
the ones for which isalnum, iscntrl,
or isspace is true or space.
isprint tests for a space or any character
for which isalnum or ispunct is true
or other ``printing character'' as
defined by the character set.
isgraph tests for any character for which
isprint is true, except for space.
isascii tests for an ASCII character (a
non-negative number less than 0200.)
The conversion functions and macros translate a
character from lowercase (uppercase) to uppercase
(lowercase).
tolower if the character is one for which
isupper is true and there a
corresponding lowercase character,
tolower returns the corresponding
lowercase character. Otherwise, the
character is returned unchanged.
toupper if the character is one for which
islower is true and there is a
corresponding uppercase character,
toupper returns the corresponding
uppercase character. Otherwise,
the character is returned unchanged.
toascii turns off the bits that are not part
of the ASCII character set.
_tolower returns the lowercase representation
of a character for which isupper is
true, otherwise undefined.
_toupper returns the uppercase representation
of a character for which islower is
true, otherwise undefined.
The conversion macros have the same functionality
of the functions on valid input, but the macros are
faster because they do not do range checking.
All the character classification macros and the
conversion functions and macros do a table lookup.
setchrclass initializes the table used by these
functions and macros to a specific character
classification set. setchrclass uses the value
of its argument or the value of the environment
variable CHRCLASS as the name of the datafile
containing the information for the desired character
set. These datafiles are searched for in the
special directory /lib/chrclass.
If chrclass is (char *)0, the value of the
environment variable CHRCLASS is used. If CHRCLASS
is not set or is undefined, the table retains its
default value. The default value is the iso8859
character set unless the executable was compiled
in a strict ANSI mode (-ansi or -ansiposix)), in
which case the default character table is ascii.
FILES
/lib/chrclass - directory containing the datafiles
for setchrclass
SEE ALSO
chrtbl(1M), stdio(3S), ascii(5), locale(3C), environ(5).
DIAGNOSTICS
If the argument to any of the character handling
macros is not in the domain of the function, the
result is undefined.
If setchrclass does not successfully fill the table,
the table will not change (initially ``ascii'') and
-1 is returned. If everything works, setchrclass
returns 0.
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