mbsrtowcs(3) - NetBSD Manual Pages

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MBSRTOWCS(3)            NetBSD Library Functions Manual           MBSRTOWCS(3)


NAME

     mbsrtowcs -- converts a multibyte character string to a wide-character
     string (restartable)


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <wchar.h>

     size_t
     mbsrtowcs(wchar_t * restrict pwcs, const char ** restrict s, size_t n,
         mbstate_t * restrict ps);


DESCRIPTION

     The mbsrtowcs() converts the multibyte character string indirectly
     pointed to by s to the corresponding wide-character string, and stores it
     in the array pointed to by pwcs.  The conversion stops due to the follow-
     ing reasons:

     ·   The conversion reaches a nul byte.  In this case, the nul byte is
         also converted.

     ·   The mbsrtowcs() has already stored n wide characters.

     ·   The conversion encounters an invalid character.

     Each character will be converted as if mbrtowc(3) is continuously called.

     After conversion, if pwcs is not a null pointer, the pointer object
     pointed to by s is a null pointer (if the conversion is stopped due to
     reaching a nul byte) or the first byte of the character just after the
     last character converted.

     If pwcs is not a null pointer and the conversion is stopped due to reach-
     ing a nul byte, the mbsrtowcs() places the state object pointed to by ps
     to an initial state after the conversion has taken place.

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

     These are the special cases:

     s == NULL || *s == NULL
                   Undefined (may cause the program to crash).

     pwcs == NULL  The conversion has taken place, but the resulting wide-
                   character string was discarded.  In this case, the pointer
                   object pointed to by s is not modified and n is ignored.

     ps == NULL    The mbsrtowcs() uses its own internal state object to keep
                   the conversion state, instead of ps mentioned in this man-
                   ual page.

                   Calling any other functions in Standard C Library (libc,
                   -lc) never changes the internal state of mbsrtowcs(), which
                   is initialized at startup time of the program.


RETURN VALUES

     mbsrtowcs() returns:

     0 or positive
                   The value returned is the number of elements stored in the
                   array pointed to by pwcs, except for a terminating nul wide
                   character (if any).  If pwcs is not NULL and the value
                   returned is equal to n, the wide-character string pointed
                   to by pwcs is not nul-terminated.  If pwcs is a null
                   pointer, the value returned is the number of elements to
                   contain the whole string converted, except for a terminat-
                   ing nul wide character.

     (size_t)-1    The array indirectly pointed to by s contains a byte
                   sequence forming invalid character.  In this case,
                   mbsrtowcs() sets errno to indicate the error.


ERRORS

     mbsrtowcs() may cause an error in the following case:

     [EILSEQ]           The pointer pointed to by s points to an invalid or
                        incomplete multibyte character.

     [EINVAL]           ps points to an invalid or uninitialized mbstate_t
                        object.


SEE ALSO

     mbrtowc(3), mbstowcs(3), setlocale(3)


STANDARDS

     The mbsrtowcs() function conforms to ISO/IEC 9899/AMD1:1995 (``ISO C90,
     Amendment 1'').  The restrict qualifier is added at ISO/IEC 9899:1999
     (``ISO C99'').

NetBSD 6.1.2                   February 4, 2002                   NetBSD 6.1.2