NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

       #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    [Toc]    [Back]

       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 (isal-
	      pha(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    [Toc]    [Back]

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

CONFORMING TO    [Toc]    [Back]

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

NOTE    [Toc]    [Back]

       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    [Toc]    [Back]

       tolower(3), toupper(3), setlocale(3), ascii(7), locale(7)




GNU				  1995-09-02			    ISALPHA(3)