linux man page for isblank

ISALPHA(3)						     Linux Programmer's Manual							ISALPHA(3)

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

SYNOPSIS
       #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);

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

       isascii():
	   _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE
       isblank():
	   _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
	   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 (isalpha(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.

       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  ('
'),  carriage
	      return ('
'), horizontal tab ('	'), 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 nonzero 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 exten-
       sion.  isblank() conforms to POSIX.1-2001 and C99 7.4.1.3.  POSIX.1-2008 marks isascii()  as  obsolete,	noting	that  it  cannot  be  used
       portably in a localized application.

NOTES
       The details of what characters belong into which class depend on the current locale.  For example, isupper() will not recognize an A-umlaut
       (A) as an uppercase letter in the default C locale.

SEE ALSO
       iswalnum(3), iswalpha(3), iswblank(3), iswcntrl(3), iswdigit(3), iswgraph(3), iswlower(3), iswprint(3),	iswpunct(3),  iswspace(3),  iswup-
       per(3), iswxdigit(3), setlocale(3), toascii(3), tolower(3), toupper(3), ascii(7), locale(7)

COLOPHON
       This  page is part of release 3.27 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
								    2010-09-20								ISALPHA(3)