ctype(3) [netbsd man page]

CTYPE(3)						   BSD Library Functions Manual 						  CTYPE(3)

NAME

     isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isblank, toupper, tolower, -- character
     classification and mapping functions

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <ctype.h>

     isalpha(int c);

     isupper(int c);

     islower(int c);

     isdigit(int c);

     isxdigit(int c);

     isalnum(int c);

     isspace(int c);

     ispunct(int c);

     isprint(int c);

     isgraph(int c);

     iscntrl(int c);

     isblank(int c);

     toupper(int c);

     tolower(int c);

DESCRIPTION

     The above functions perform character tests and conversions on the integer c.

     See the specific manual pages for information about the test or conversion performed by each function.

EXAMPLES

     To print an upper-case version of a string to stdout, the following code can be used:

	   const char *s = "xyz";

	   while (*s != '') {
	       putchar(toupper((int)(unsigned char)*s));
	       s++;
	   }

SEE ALSO

     isalnum(3), isalpha(3), isblank(3), iscntrl(3), isdigit(3), isgraph(3), islower(3), isprint(3), ispunct(3), isspace(3), isupper(3),
     isxdigit(3), tolower(3), toupper(3), ascii(7)

STANDARDS

     These functions, with the exception of isblank(), conform to ANSI X3.159-1989 (``ANSI C89'').  All described functions, including isblank(),
     also conform to IEEE Std 1003.1-2001 (``POSIX.1'').

CAVEATS

     The first argument of these functions is of type int, but only a very restricted subset of values are actually valid.  The argument must
     either be the value of the macro EOF (which has a negative value), or must be a non-negative value within the range representable as unsigned
     char.  Passing invalid values leads to undefined behavior.

     Values of type int that were returned by getc(3), fgetc(3), and similar functions or macros are already in the correct range, and may be
     safely passed to these ctype functions without any casts.

     Values of type char or signed char must first be cast to unsigned char, to ensure that the values are within the correct range.  The result
     should then be cast to int to avoid warnings from some compilers.	Casting a negative-valued char or signed char directly to int will produce
     a negative-valued int, which will be outside the range of allowed values (unless it happens to be equal to EOF, but even that would not give
     the desired result).

BSD
								    May 6, 2010 							       BSD

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)