Provided by: manpages-dev_3.21-1_all bug

NAME

       isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower,
       isprint, ispunct, isspace, isupper, isxdigit - character classification
       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; 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  ('\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.  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
       (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),   setlocale(3),   toascii(3),  tolower(3),
       toupper(3), ascii(7), locale(7)

COLOPHON

       This page is part of release 3.21 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/.