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MBTOWC(3)			   BSD Library Functions Manual 			MBTOWC(3)

NAME
     mbtowc -- converts a multibyte character to a wide character

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <stdlib.h>

     int
     mbtowc(wchar_t * restrict pwc, const char * restrict s, size_t n);

DESCRIPTION
     mbtowc() usually converts the multibyte character pointed to by s to a wide character, and
     stores it in the wchar_t object pointed to by pwc if pwc is non-NULL and s points to a valid
     character.  This function may inspect at most n bytes of the array beginning from s.

     In state-dependent encodings, s may point to the special sequence bytes to change the shift-
     state.  Although such sequence bytes correspond to no individual wide-character code,
     mbtowc() changes its own state by the sequence bytes and treats them as if they are a part
     of the subsequence multibyte character.

     Unlike mbrtowc(3), the first n bytes pointed to by s need to form an entire multibyte char-
     acter.  Otherwise, this function causes an error.

     Calling any other functions in Standard C Library (libc, -lc) never changes the internal
     state of mbtowc(), except for calling setlocale(3) with changing the LC_CTYPE category of
     the current locale.  Such setlocale(3) call causes the internal state of this function to be
     indeterminate.

     The behaviour of mbtowc() is affected by the LC_CTYPE category of the current locale.

     There are special cases:

     s == NULL	   mbtowc() initializes its own internal state to an initial state, and deter-
		   mines whether the current encoding is state-dependent.  This function returns
		   0 if the encoding is state-independent, otherwise non-zero.	In this case, pwc
		   is completely ignored.

     pwc == NULL   mbtowc() executes the conversion as if pwc is non-NULL, but a result of the
		   conversion is discarded.

     n == 0	   In this case, the first n bytes of the array pointed to by s never form a com-
		   plete character.  Thus, the mbtowc() always fails.

RETURN VALUES
     Normally, the mbtowc() returns:

     0		   s points to a nul byte ('\0').

     positive	   Number of bytes for the valid multibyte character pointed to by s.  There are
		   no cases that the value returned is greater than the value of the MB_CUR_MAX
		   macro.

     -1 	   s points to an invalid or an incomplete multibyte character.  The mbtowc()
		   also sets errno to indicate the error.

     When s is equal to NULL, mbtowc() returns:

     0		 The current encoding is state-independent.

     non-zero	 The current encoding is state-dependent.

ERRORS
     mbtowc() may cause an error in the following case:

     [EILSEQ]		s points to an invalid or incomplete multibyte character.

SEE ALSO
     mblen(3), mbrtowc(3), setlocale(3)

STANDARDS
     The mbtowc() function conforms to ANSI X3.159-1989 (``ANSI C89'').  The restrict qualifier
     is added at ISO/IEC 9899:1999 (``ISO C99'').

BSD					 February 3, 2002				      BSD
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