NAME

     isalnum,  isalpha,  isascii,  isblank,   iscntrl,   isdigit,
     isgraph, islower, isprint, ispunct, isspace, isupper, isxdi-
     git - character classification routines


SYNOPSIS

     #include <ctype.h>

     int isalnum (int c);
     int isalpha (int c);
     int isascii (int c);
     int isblank (int c);
     int iscntrl (int c);
     int isdigit (int c);
     int isgraph (int c);
     int islower (int c);
     int isprint (int c);
     int ispunct (int c);
     int isspace (int c);
     int isupper (int c);
     int isxdigit (int c);


DESCRIPTION

     These functions check whether c, which must have  the  value
     of  an  unsigned char or EOF, falls into a certain character
     class according to the current locale.

     isalnum()
          checks for an alphanumeric character; it is  equivalent
          to (isalpha(c) || isdigit(c)).

     isalpha()
          checks for an alphabetic character; in the standard "C"
          locale, it is equivalent to (isupper(c) || islower(c)).
          In some locales, there may be additional characters for
          which  isalpha()  is  true--letters  which  are neither
          upper case nor lower case.

     isascii()
          checks whether c is a 7-bit unsigned  char  value  that
          fits  into the ASCII character set.  This function is a
          BSD extension and is also an SVID extension.

     isblank()
          checks for a blank character; that is,  a  space  or  a
          tab.  This function is a GNU extension.

     iscntrl()
          checks for a control character.

     isdigit()
          checks for a digit (0 through 9).

     isgraph()
          checks for any printable character except space.

     islower()
          checks for a lower - case character.

     isprint()
          checks for any printable character including space.

     ispunct()
          checks for any printable character which is not a space
          or an alphanumeric character.

     isspace()
          checks for white - space characters.  In the "" "C" and
          "" "POSIX" locales, these are: space, form-feed ('\f'),
          newline ('\n'), carriage return ('\r'), horizontal  tab
          ('\t'), and vertical tab ('\v').

     isupper()
          checks for an uppercase letter.

     isxdigit()
          checks for a hexadecimal digits, i.e. one of 0 1 2 3  4
          5 6 7 8 9 a b c d e f A B C D E F.


RETURN VALUE

     The values returned are nonzero if  the  character  c  falls
     into the tested class, and a zero value if not.


CONFORMING TO

     ANSI - C, BSD 4.3.  isascii() is a BSD extension and is also
     an SVID extension.  isblank() is a GNU extension.


NOTE

     The details of  what  characters  belong  into  which  class
     depend  on  the current locale.  For example, isupper() will
     not recognize an A - umlaut as an uppercase  letter  in  the
     default C locale.


SEE ALSO

     tolower(3), toupper(3), setlocale(3),