ctype(3C)                         SDK R4.11                        ctype(3C)


NAME
       ctype: isdigit, isxdigit, islower, isupper, isalpha, isalnum,
       isspace, iscntrl, ispunct, isprint, isgraph, isascii - character
       handling

SYNOPSIS
       #include <ctype.h>
       int isalpha(int c);
       int isupper(int c);
       int islower(int c);
       int isdigit(int c);
       int isxdigit(int c);
       int isalnum(int c);
       int isspace(int c);
       int ispunct(int c);
       int isprint(int c);
       int isgraph(int c);
       int iscntrl(int c);
       int isascii(int c);

DESCRIPTION
       These macros classify character-coded integer values.  Each is a
       predicate returning non-zero for true, zero for false.  The behavior
       of these macros, except isascii, is affected by the current locale
       [see setlocale(3C)].  To modify the behavior, change the LC_CTYPE
       category using setlocale, that is, setlocale (LC_CTYPE, newlocale),
       or setlocale (LC_ALL, newlocale).  In the C locale, or in a locale
       where character type information is not defined, characters are
       classified according to the rules of the US-ASCII 7-bit coded
       character set.

       The macro isascii is defined on all integer values; the rest are
       defined only where the argument is an int, the value of which is
       representable as an unsigned char, or EOF, which is defined by the
       stdio.h header file and represents end-of-file.

       isalpha        tests for any character for which isupper or islower
                      is true, or any character that is one of an
                      implementation-defined set of characters for which
                      none of iscntrl, isdigit, ispunct, or isspace is true.
                      In the C locale, isalpha returns true only for the
                      characters for which isupper or islower is true.

       isupper        tests for any character that is an upper-case letter
                      or is one of an implementation-defined set of
                      characters for which none of iscntrl, isdigit,
                      ispunct, isspace, or islower is true.  In the C
                      locale, isupper returns true only for the characters
                      defined as upper-case ASCII characters.

       islower        tests for any character that is a lower-case letter or
                      is one of an implementation-defined set of characters
                      for which none of iscntrl, isdigit, ispunct, isspace,
                      or isupper is true.  In the C locale, islower returns
                      true only for the characters defined as lower-case
                      ASCII characters.

       isdigit        tests for any decimal-digit character.

       isxdigit       tests for any hexadecimal-digit character ([0-9],
                      [A-F] or [a-f]).

       isalnum        tests for any character for which isalpha or isdigit
                      is true (letter or digit).

       isspace        tests for any space, tab, carriage-return, newline,
                      vertical-tab or form-feed (standard white-space
                      characters) or for one of an implementation-defined
                      set of characters for which isalnum is false.  In the
                      C locale, isspace returns true only for the standard
                      white-space characters.

       ispunct        tests for any printing character which is neither a
                      space nor a character for which isalnum is true.

       isprint        tests for any printing character, including the space
                      character (" ").

       isgraph        tests for any printing character, except space.

       iscntrl        tests for any ``control character'' as defined by the
                      character set.

       isascii        tests for the ASCII character codes between 0 and
                      octal 0177 inclusive.

       All the character classification macros and the conversion functions
       and macros use a table lookup.

       Functions exist for all the above-defined macros.  To get the
       function form, the macro name must be undefined (e.g., #undef
       isdigit).


   Considerations for Threads Programming
                     +---------+-----------------------------+
                     |         |                      async- |
                     |function | reentrant   cancel   cancel |
                     |         |             point     safe  |
                     +---------+-----------------------------+
                     |isalnum  |     Y         N        N    |
                     |isalpha  |     Y         N        N    |
                     |isascii  |     Y         N        N    |
                     |iscntrl  |     Y         N        N    |
                     |isdigit  |     Y         N        N    |
                     |isgraph  |     Y         N        N    |
                     |islower  |     Y         N        N    |
                     |isprint  |     Y         N        N    |
                     |ispunct  |     Y         N        N    |
                     |isspace  |     Y         N        N    |
                     |isupper  |     Y         N        N    |
                     |isxdigit |     Y         N        N    |
                     +---------+-----------------------------+
       The above functions should be called when the other threads in a
       process are not changing the LC_CTYPE information.  See the
       setlocale(3C) man page for more information.


FILES
       /usr/lib/locale/locale/LC_CTYPE

DIAGNOSTICS
       If the argument to any of the character handling macros is not in the
       domain of the function, the result is undefined.

SEE ALSO
       chrtbl(1M), setlocale(3C), stdio(3S), ascii(5), environ(5),
       reentrant(3).


Licensed material--property of copyright holder(s)