WCSRTOMBS(3) Library Functions Manual WCSRTOMBS(3)
wcsrtombs -- converts a wide-character string to a multibyte character
Standard C Library (libc, -lc)
wcsrtombs(char * restrict s, const wchar_t ** restrict pwcs, size_t
n, mbstate_t * restrict ps);
The wcsrtombs() converts the nul-terminated wide-character string
indirectly pointed to by pwcs to the corresponding multibyte character
string, and stores it in the array pointed to by s. The conversion stops
due to the following reasons:
o The conversion reaches a nul wide character. In this case, the nul
wide character is also converted.
o The wcsrtombs() has already stored n bytes in the array pointed to by
o The conversion encounters an invalid character.
Each character will be converted as if wcrtomb(3) is continuously called,
except the internal state of wcrtomb(3) will not be affected.
After conversion, if s is not a null pointer, the pointer object pointed
to by pwcs is a null pointer (if the conversion is stopped due to
reaching a nul wide character) or the first byte of the character just
after the last character converted.
If s is not a null pointer and the conversion is stopped due to reaching
a nul wide character, wcsrtombs() places the state object pointed to by
ps to an initial state after the conversion is taken place.
The behaviour of wcsrtombs() is affected by the LC_CTYPE category of the
These are the special cases:
s == NULL wcsrtombs() returns the number of bytes to store the whole
multibyte character string corresponding to the wide-
character string pointed to by pwcs, not including the
terminating nul byte. In this case, n is ignored.
pwcs == NULL || *pwcs == NULL
Undefined (may cause the program to crash).
ps == NULL wcsrtombs() uses its own internal state object to keep the
conversion state, instead of ps mentioned in this manual
Calling any other functions in Standard C Library (libc,
-lc) never changes the internal state of wcsrtombs(), which
is initialized at startup time of the program.
0 or positive
Number of bytes stored in the array pointed to by s, except
for a nul byte. There are no cases that the value returned
is greater than n (unless s is a null pointer). If the
return value is equal to n, the string pointed to by s will
not be nul-terminated.
(size_t)-1 pwcs points to a string containing an invalid wide
character. The wcsrtombs() also sets errno to indicate the
wcsrtombs() may cause an error in the following case:
[EILSEQ] pwcs points to a string containing an invalid wide
setlocale(3), wcrtomb(3), wcstombs(3)
The wcsrtombs() function conforms to ANSI X3.159-1989 (``ANSI C89'').
The restrict qualifier is added at ISO/IEC 9899:1999 (``ISO C99'').
NetBSD 6.1.5 August 8, 2006 NetBSD 6.1.5