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CTYPE(3V)                                                            CTYPE(3V)



NAME
       ctype,  conv,  isalpha,  isupper,  islower, isdigit, isxdigit, isalnum,
       isspace, ispunct, isprint, iscntrl, isascii, isgraph, toupper, tolower,
       toascii - character classification and conversion macros and functions

SYNOPSIS
       #include <&lt;ctype.h>&gt;

       isalpha(c)

       ...

DESCRIPTION
   Character Classification Macros
       These  macros  classify character-coded integer values according to the
       rules of the coded character set defined by the character type informa-
       tion  in  the program's locale (category LC_CTYPE).  On program startup
       the LC_CTYPE category of locale is equivalent to the "C" locale.

       In the "C" locale, or in a locale where the character type  information
       is not defined, characters are classified according to the rules of the
       US-ASCII 7-bit coded character set.  The control characters  are  those
       below 040 (and the single byte 0177) (DEL).  See ascii(7).

       In all cases that argument is an int, the value of which must be repre-
       sentable as an unsigned char or must equal the value of the macro  EOF.
       If the argument has any other value, the behavior is undefined.

       Each  is a predicate returning nonzero for true, zero for false.  isas-
       cii() is defined on all integer values.

       isalpha(c)          c is a letter.

       isupper(c)          c is an upper case letter.

       islower(c)          c is a lower case letter.

       isdigit(c)          c is a digit [0-9].

       isxdigit(c)         c is a hexadecimal digit [0-9], [A-F], or [a-f].

       isalnum(c)          c is an alphanumeric character, that  is,  c  is  a
                           letter or a digit.

       isspace(c)          c  is  a  SPACE, TAB, RETURN, NEWLINE, FORMFEED, or
                           vertical tab character.

       ispunct(c)          c is a punctuation character (neither  control  nor
                           alphanumeric).

       isprint(c)          c is a printing character.

       iscntrl(c)          c is a delete character or ordinary control charac-
                           ter.

       isascii(c)          c is an ASCII character, code less than 0200.

       isgraph(c)          c is a visible graphic character.

   Character Conversion Macros
       toascii(c)
              Masks c with the correct value so that c is guaranteed to be  an
              ASCII  character  in the range 0 through 0x7f.  Will not perform
              mapping from a non-ASCII coded character set into ASCII.

   Character Conversion Functions
       These functions perform simple conversions on single characters.   They
       replace  the previous macro definitions which did not extend to support
       variant settings of the LC_CTYPE locale category.

       toupper(c)          Converts c  to  its  upper-case  equivalent.   This
                           function  works  correctly  for all coded character
                           sets and all characters within such  sets  selected
                           by a valid setting of the LC_CTYPE locale category.

       tolower(c)          Converts  c  to  its  lower-case  equivalent.  This
                           function works correctly for  all  coded  character
                           sets  and  all characters within such sets selected
                           by a valid setting of the LC_CTYPE locale category.

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

SYSTEM V DESCRIPTION
   Character Conversion Macros
       The  macros  _toupper()  and  _tolower() are faster than the equivalent
       functions (toupper()  and  tolower())  but  only  work  properly  on  a
       restricted  range  of characters, and will not work on a LC_CTYPE cate-
       gory other than the default "C" (ASCII).

       These macros perform simple conversions on single characters.

       _toupper(c)         converts c to  its  upper-case  equivalent.   Note:
                           This only works where c is known to be a lower-case
                           character to start with (presumably  checked  using
                           islower()).

       _tolower(c)         converts  c  to  its  lower-case equivalent.  Note:
                           This only works where c is known to be a upper-case
                           character  to  start with (presumably checked using
                           isupper()).

SEE ALSO
       setlocale(3V), ascii(7), iso_8859_1(7)



                                11 January 1990                      CTYPE(3V)