NAME
      isalpha(), isupper(), islower(), isdigit(), isxdigit(), isalnum(),
      isspace(), ispunct(), isprint(), isgraph(), iscntrl(), isascii() -
      classify characters

 SYNOPSIS
      #include 

      int isalnum(int c);
      int isalpha(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);
      int isascii(int c);

 DESCRIPTION
      These functions classify character-coded integer values according to
      the rules of the coded character set identified by the last successful
      call to setlocale() (see setlocale(3C)).	Each function is a predicate
      returning non-zero for true, zero for false.

      If setlocale() has not been called successfully, characters are
      classified according to the rules of the default ASCII 7-bit coded
      character set (see setlocale(3C)).

      isascii() is defined on all integer values; the other functions are
      defined for the range -1 (EOF) through 255.

      The functions return non-zero under the following circumstances; zero
      otherwise:

	   isalpha(c)	     c is a letter.

	   isupper(c)	     c is an uppercase letter.

	   islower(c)	     c is a lowercase letter.

	   isdigit(c)	     c is a decimal digit (in ASCII: characters [0-
			     9]).

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

	   isalnum(c)	     c is an alphanumeric (letters or digits).

	   isspace(c)	     c is a character that creates ``white space''
			     in displayed text (in ASCII: space, tab,
			     carriage return, new-line, vertical tab, and
			     form-feed).

	   ispunct(c)	     c is a punctuation character (in ASCII: any
			     printing character except the space character
			     (040), digits, letters).

	   isprint(c)	     c is a printing character.

	   isgraph(c)	     c is a visible character (in ASCII: printing
			     characters, excluding the space character
			     (040)).

	   iscntrl(c)	     c is a control character (in ASCII: character
			     codes less than 040 and the delete character
			     (0177)).

	   isascii(c)	     c is any ASCII character code between 0 and
			     0177, inclusive.

      If the argument to any of these functions is outside the domain of the
      function, the result is undefined.

 WARNINGS
      These functions are supplied both as library functions and as macros
      defined in the  header.	Normally, the macro versions are
      used.  To obtain the library function, either use a #undef to remove
      the macro definition or, if compiling in ANSI-C mode, enclose the
      function name in parenthesis or take its address.	 The following
      example uses the library functions for isalpha(), isdigit(), and
      isspace():

	   #include 
	   #undef isalpha
		...
	   main()
	   {
	       int (*ctype_func)();
		   ...
	       if ( isalpha(c) )
		   ...
	       if ( (isdigit)(c) )
		   ...
	       ctype_func = isspace;
		   ...
	   }