MBSRTOWCS(3) Library Functions Manual MBSRTOWCS(3)
mbsrtowcs -- converts a multibyte character string to a wide-character
Standard C Library (libc, -lc)
mbsrtowcs(wchar_t * restrict pwcs, const char ** restrict s, size_t
n, mbstate_t * restrict ps);
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
o The conversion reaches a nul byte. In this case, the nul byte is
o The mbsrtowcs() has already stored n wide characters.
o 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
reaching 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
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
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.
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
terminating 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.
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
mbrtowc(3), mbstowcs(3), setlocale(3)
The mbsrtowcs() function conforms to ISO/IEC 9899/AMD1:1995 (``ISO C90,
Amendment 1''). The restrict qualifier is added at ISO/IEC 9899:1999
NetBSD 6.1.5 February 4, 2002 NetBSD 6.1.5