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NAME

       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

SYNOPSIS

       #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)):

       isascii():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE

       isblank():
           _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(),
       isupper_l(), isxdigit_l():
           Since glibc 2.10:
                  _XOPEN_SOURCE >= 700
           Before glibc 2.10:
                  _GNU_SOURCE

       isascii_l():
           Since glibc 2.10:
                  _XOPEN_SOURCE >= 700 && (_SVID_SOURCE || _BSD_SOURCE)
           Before glibc 2.10:
                  _GNU_SOURCE

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 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
       handle.

       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.

       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 uppercase nor lowercase.

       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 lowercase 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  (''),  newline  ('
'),
              carriage  return ('
'), horizontal tab ('	'), and vertical tab
              ('').

       isupper()
              checks for an uppercase letter.

       isxdigit()
              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.

RETURN VALUE

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

ATTRIBUTES

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

VERSIONS

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

CONFORMING TO

       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(),
       iscntrl_l(),  isdigit_l(),   isgraph_l(),   islower_l(),   isprint_l(),
       ispunct_l(), isspace_l(), isupper_l(), and isxdigit_l().

       isascii_l() is a GNU extension.

NOTES

       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.

SEE ALSO

       iswalnum(3),   iswalpha(3),   iswblank(3),   iswcntrl(3),  iswdigit(3),
       iswgraph(3),  iswlower(3),   iswprint(3),   iswpunct(3),   iswspace(3),
       iswupper(3),  iswxdigit(3),  newlocale(3),  setlocale(3), uselocale(3),
       toascii(3), tolower(3), toupper(3), ascii(7), locale(7)

COLOPHON

       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 http://www.kernel.org/doc/man-pages/.



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