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NetBSD 6.1.5 - man page for ctype (netbsd section 3)

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

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

     Standard C Library (libc, -lc)

     #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);

     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

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

	   const char *s = "xyz";

	   while (*s != '\0') {
	       putchar(toupper((int)(unsigned char)*s));

     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),

     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'').

     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 warn-
     ings 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

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