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



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

SYNOPSIS
       #include 

       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);

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.  This function is a BSD extension and is also an SVID extension.

       isblank()
              checks  for  a  blank character; that is, a space or a tab.  This function is a GNU
              extension.

       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  charac-
              ter.

       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, i.e. 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
       ANSI - C, BSD 4.3.  isascii() is a BSD extension and is also an SVID extension.  isblank()
       is a GNU extension.

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

SEE ALSO
       tolower(3), toupper(3), setlocale(3), ascii(7), locale(7)




GNU                                         1995-09-02                                 ISALPHA(3)