ctype(3C)               LIBRARY FUNCTIONS               ctype(3C)



NAME
     ctype: isdigit, isxdigit, islower, isupper,  isalpha,  isal-
     num,  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 LCTYPE category in setlocale(3C), that
     is,  setlocale (LCCTYPE, 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  charac-
                    ters  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.




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ctype(3C)               LIBRARY FUNCTIONS               ctype(3C)



     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
                    space (" ").

     isgraph        tests  for  any  printing  character,  except
                    space.

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

     isascii        tests for any ASCII character, code between 0
                    and 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).

FILES
     /usr/lib/locale/locale/LCCTYPE

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



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ctype(3C)               LIBRARY FUNCTIONS               ctype(3C)



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




















































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