ctype(3)						     Library Functions Manual							  ctype(3)

NAME

       isalnum, isalpha, isascii, iscntrl, isdigit, isgraph, islower, isprint, ispunct, isspace, isupper, isxdigit - Classify characters

LIBRARY

       Standard C Library (libc)

SYNOPSIS

       #include <ctype.h>

       int isalnum(
	       int c);

       int isalpha(
	       int c);

       int isascii(
	       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);

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       isalnum(), isalpha(), isascii(), iscntrl(), isdigit(), isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(), isxdigit(): XSH5.0

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Specifies  the  character to be tested. In all cases, this parameter is an  int data type, whose value must be representable as an unsigned
       char or must equal the value of the macro EOF (defined in the stdio.h include file). When this parameter has a value that cannot be  repre-
       sented as an unsigned char or EOF, the result is undefined.

DESCRIPTION

       The ctype functions test for membership in a character class in the current locale.  Each function tests to see if a character is part of a
       different character class.

       If the character is part of the character class, the function returns a nonzero value for true; otherwise, the function returns a value	of
       0 (zero) for false.

       Each  function is named by adding the prefix is to the name of the character class for which the function tests. For example, the isalpha()
       function tests whether the character specified by the c parameter belongs to the alpha class.

       The following lists the function names and describes the conditions under which the functions return a true value.  When c is  a  character
       of class alpha or class digit in the program's current locale.  When c is a character of class alpha in the program's current locale. Char-
       acters in classes lower and upper automatically belong to class alpha.  When c is a 7-bit US-ASCII character whose value is in the range  0
       to  0177  (0  to  0x7F),  inclusive.  When c is a character of class cntrl in the program's current locale.  When c is a character of class
       digit in the program's current locale. The following characters are included in this class:

	      0 1 2 3 4 5 6 7 8 9 When c is a character of class graph in the program's current locale. Characters in classes  alpha,  digit,  and
	      punct  are  automatically in class graph.  Unlike isprint(), isgraph() returns FALSE for the space character.  When c is a character
	      of class lower in the program's current locale. At a minimum, the 26 lowercase US-ASCII characters are included in this class. These
	      are:

	      a  b c d e f g h i j k l m n o p q r s t u v w x y z When c is a character of class print in the program's current locale. All char-
	      acters in the class graph and the space character are automatically included in the class print.	When c is  a  character  of  class
	      punct  in  the  program's  current  locale.  When c is a character of class space in the program's current locale. At a minimum, the
	      space, form-feed, newline, carriage-return, tab, and vertical-tab characters are included in this class.	When c is a  character	of
	      class  upper  in	the program's current locale. At a minimum, the 26 uppercase US-ASCII characters are included in this class. These
	      are:

	      A B C D E F G H I J K L M N O P Q R S T U V W X Y Z When c is a character of class xdigit in the program's current locale. The  fol-
	      lowing characters are included in this class:

	      0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f

NOTES

       The LC_CTYPE category of the current locale affects all conversions.

       In  the	C  locale, or in a locale where character-type information is not defined, characters are classified according to the rules of the
       ASCII character set.  For any character value greater than octal 177 (0177 in C-language context) the value 0 (zero) is returned.

       [Tru64 UNIX]  The isdigit(), isxdigit(), and isalnum() functions do not recognize Thai digits. Many applications make assumptions about how
       a  digit  character can be converted to its numeric equivalent.	Changing the functions to recognize Thai digits would break these applica-
       tions. Refer to TACTIS(5) for more information about Thai digits.

RETURN VALUES

       Upon successful completion of any function, a nonzero (TRUE) value is returned.	Otherwise, the value 0 (FALSE) is returned.

RELATED INFORMATION

       Files: locale(4)

       Functions: ctype(3), setlocale(3), wctype(3)

       Standards: i18n_intro(5), standards(5) delim off

																	  ctype(3)