isdigit(3) [redhat man page]

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

NAME

       isalnum,  isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower, isprint, ispunct, isspace, isupper, isxdigit - character classifi-
       cation 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);

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 character.

       isspace()
	      checks  for  white-space	characters.   In the "C" and "POSIX" locales, these are: space, form-feed ('f'), newline ('
'), carriage
	      return ('
'), horizontal tab ('	'), 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)

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

NAME

       isalnum,  isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower, isprint, ispunct, isspace, isupper, isxdigit - character classifi-
       cation 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);

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 character.

       isspace()
	      checks  for  white-space	characters.   In the "C" and "POSIX" locales, these are: space, form-feed ('f'), newline ('
'), carriage
	      return ('
'), horizontal tab ('	'), 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)