ctype(3C)       UNIX System V(C Programming Language Utilities)       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 LCTYPE category in
      setlocale, 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 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


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ctype(3C)       UNIX System V(C Programming Language Utilities)       ctype(3C)


                     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).

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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