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, 0 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_TYPE category in  setlocale(),  that
     is, setlocale(LC_CTYPE, 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.

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