ISALPHA(3)		   Linux Programmers Manual		   ISALPHA(3)



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

SYNOPSIS
       #include 

       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);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       isascii(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE
       isblank(): _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99

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 (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 trueletters 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.

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

       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, that is, 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 non-zero if the	character  c  falls  into  the
       tested class, and a zero value if not.

CONFORMING TO
       C99, 4.3BSD.  C89 specifies all of these functions except isascii() and
       isblank().  isascii() is a BSD extension and is also an SVr4 extension.
       isblank() conforms to POSIX.1-2001 and C99 7.4.1.3.

NOTES
       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
       iswalnum(3),  iswalpha(3),  iswblank(3), iswcntrl(3), iswdigit(3), isw
       graph(3), iswlower(3), iswprint(3),  iswpunct(3),  iswspace(3),	iswup
       per(3),	iswxdigit(3),  setlocale(3), tolower(3), toupper(3), ascii(7),
       locale(7)

COLOPHON
       This page is part of release 3.05 of the Linux  man-pages  project.   A
       description  of	the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.



GNU				  2007-07-26			    ISALPHA(3)