Provided by: manpages-dev_6.8-2_all bug

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

LIBRARY

       Standard C library (libc, -lc)

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():
           _XOPEN_SOURCE
               || /* glibc >= 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _SVID_SOURCE

       isblank():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

       salnum_l(), salpha_l(), sblank_l(), scntrl_l(), sdigit_l(), sgraph_l(), slower_l(),
       sprint_l(), spunct_l(), sspace_l(), supper_l(), sxdigit_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 ('\f'), newline ('\n'), carriage  return  ('\r'),  horizontal  tab
              ('\t'), and vertical tab ('\v').

       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

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │InterfaceAttributeValue   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │isalnum(), isalpha(), isascii(), isblank(), iscntrl(),         │ Thread safety │ MT-Safe │
       │isdigit(), isgraph(), islower(), isprint(), ispunct(),         │               │         │
       │isspace(), isupper(), isxdigit()                               │               │         │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       isalnum()
       isalpha()
       iscntrl()
       isdigit()
       isgraph()
       islower()
       isprint()
       ispunct()
       isspace()
       isupper()
       isxdigit()
       isblank()
              C11, POSIX.1-2008.

       isascii()
       isalnum_l()
       isalpha_l()
       isblank_l()
       iscntrl_l()
       isdigit_l()
       isgraph_l()
       islower_l()
       isprint_l()
       ispunct_l()
       isspace_l()
       isupper_l()
       isxdigit_l()
              POSIX.1-2008.

       isascii_l()
              GNU.

HISTORY

       isalnum()
       isalpha()
       iscntrl()
       isdigit()
       isgraph()
       islower()
       isprint()
       ispunct()
       isspace()
       isupper()
       isxdigit()
              C89, POSIX.1-2001.

       isblank()
              C99, POSIX.1-2001.

       isascii()
              POSIX.1-2001 (XSI).

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

       isalnum_l()
       isalpha_l()
       isblank_l()
       iscntrl_l()
       isdigit_l()
       isgraph_l()
       islower_l()
       isprint_l()
       ispunct_l()
       isspace_l()
       isupper_l()
       isxdigit_l()
              glibc 2.3.  POSIX.1-2008.

       isascii_l()
              glibc 2.3.

CAVEATS

       The  standards  require  that  the argument c for these functions is either EOF or a value
       that is representable in the type unsigned char; otherwise, the behavior is undefined.  If
       the  argument  c  is  of  type char, it must be cast to unsigned char, as in the following
       example:

           char c;
           ...
           res = toupper((unsigned char) c);

       This is necessary because char may be the equivalent of signed char, in which case a  byte
       where  the  top bit is set would be sign extended when converting to int, yielding a value
       that is outside the range of unsigned char.

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