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

       isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower,
       isprint, ispunct, isspace,  isupper,  isxdigit,	isalnum_l,  isalpha_l,
       isascii_l,   isblank_l,	iscntrl_l,  isdigit_l,	isgraph_l,  islower_l,
       isprint_l, ispunct_l,  isspace_l,  isupper_l,  isxdigit_l  -  character
       classification functions

       #include <ctype.h>

       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);
       int isblank(int c);

       int isalnum_l(int c, locale_t locale);
       int isalpha_l(int c, locale_t locale);
       int isblank_l(int c, locale_t locale);
       int iscntrl_l(int c, locale_t locale);
       int isdigit_l(int c, locale_t locale);
       int isgraph_l(int c, locale_t locale);
       int islower_l(int c, locale_t locale);
       int isprint_l(int c, locale_t locale);
       int ispunct_l(int c, locale_t locale);
       int isspace_l(int c, locale_t locale);
       int isupper_l(int c, locale_t locale);
       int isxdigit_l(int c, locale_t locale);

       int isascii_l(int c, locale_t locale);

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


	   _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
	   _POSIX_C_SOURCE >= 200112L;
	   or cc -std=c99

       isalnum_l(), isalpha_l(), isblank_l(), iscntrl_l(), isdigit_l(),
       isgraph_l(), islower_l(), isprint_l(), ispunct_l(), isspace_l(), isup‐
       per_l(), isxdigit_l():
	   Since glibc 2.10:
		  _XOPEN_SOURCE >= 700
	   Before glibc 2.10:

	   Since glibc 2.10:
	   Before glibc 2.10:

       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 specified locale.  The functions without the	 "_l"  suffix  perform
       the check based on the current locale.

       The  functions  with  the  "_l"	suffix	perform the check based on the
       locale specified by the locale object locale.  The  behavior  of	 these
       functions   is  undefined  if  locale  is  the  special	locale	object
       LC_GLOBAL_LOCALE (see duplocale(3)) or is not  a	 valid	locale	object

       The list below explains the operation of the functions without the "_l"
       suffix; the functions with the "_l" suffix differ  only	in  using  the
       locale object locale instead of the current locale.

	      checks for an alphanumeric character; it is equivalent to (isal‐
	      pha(c) || isdigit(c)).

	      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 uppercase nor lowercase.

	      checks  whether  c is a 7-bit unsigned char value that fits into
	      the ASCII character set.

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

	      checks for a control character.

	      checks for a digit (0 through 9).

	      checks for any printable character except space.

	      checks for a lowercase character.

	      checks for any printable character including space.

	      checks for any printable character which is not a	 space	or  an
	      alphanumeric character.

	      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

	      checks for an uppercase letter.

	      checks for 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.

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

   Multithreading (see pthreads(7))
       The  isalnum(),	isalpha(), isascii(), isblank(), iscntrl(), isdigit(),
       isgraph(), islower(), isprint(), ispunct(), isspace(),  isupper(),  and
       isxdigit() functions are thread-safe.

       isalnum_l(),   isalpha_l(),   isblank_l(),   iscntrl_l(),  isdigit_l(),
       isgraph_l(), islower_l(), isprint_l(), ispunct_l(), isspace_l(),	 isup‐
       per_l(), isxdigit_l(), and isascii_l() are available since glibc 2.3.

       C89  specifies  isalnum(),  isalpha(), iscntrl(), isdigit(), isgraph(),
       islower(), isprint(), ispunct(), isspace(), isupper(), and  isxdigit(),
       but  not	 isascii()  and	 isblank().  POSIX.1-2001 also specifies those
       functions, and also isascii() (as an XSI extension) and isblank().  C99
       specifies all of the preceding functions, except isascii().

       POSIX.1-2008 marks isascii() as obsolete, noting that it cannot be used
       portably in a localized application.

       POSIX.1-2008 specifies  isalnum_l(),  isalpha_l(),  isblank_l(),	 iscn‐
       trl_l(),	   isdigit_l(),	   isgraph_l(),	   islower_l(),	  isprint_l(),
       ispunct_l(), isspace_l(), isupper_l(), and isxdigit_l().

       isascii_l() is a GNU extension.

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

       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),	 newlocale(3),	 setlocale(3),	 uselocale(3),
       toascii(3), tolower(3), toupper(3), ascii(7), locale(7)

       This  page  is  part of release 3.65 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at

GNU				  2014-03-18			    ISALPHA(3)

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