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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 character.  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 determines 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 complete 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
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS