wcsrtombs - converts a wide character string to a multibyte character
Standard C Library (libc, -lc)
wcsrtombs(const char * restrict s, const wchar_t ** restrict pwcs,
size_t n, mbstate_t * restrict ps);
The wcsrtombs() converts the null-terminated wide character string indirectly
pointed by pwcs to the corresponding multibyte character string,
and store it to the array pointed by s. The conversion stops due to the
+o The conversion reaches a null wide character. In this case, the null
wide character is also converted.
+o The wcsrtombs() has already stored n bytes to the array pointed by s.
+o The conversion encounters an invalid character.
Each characters 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 NULL pointer, the pointer object pointed by
pwcs is NULL pointer (if the conversion is stopped due to reach a null
wide character) or the first byte of the character just after the last
If s is not null pointer and the conversion is stopped due to reach a
null wide character, the wcsrtombs() places the state object pointed by
ps to an initial state after the conversion is taken place.
The behaviour of the wcsrtombs() is affected by LC_CTYPE category of the
There are special cases:
s == NULL The wcsrtombs() returns the number of bytes to store the
whole multibyte character string corresponding to the wide
character string pointed by pwcs, not including the terminating
null byte. In this case, n is ignored.
pwcs == NULL || *pwcs == NULL
undefined (may causes the program to crash).
ps == NULL The wcsrtombs() uses its own internal state object to keep
the conversion state, instead of ps mentioned in this manual
Calling any other functions in the Standard C Library
(libc, -lc) never change the internal state of the
wcsrtombs(), that is initialized at startup time of the
The wcsrtombs() returns:
0 or positive
number of bytes stored to the array pointed by s, except
for a null byte. There is 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 by s will
not be null-terminated.
(size_t)-1 pwcs points the string containing invalid wide character.
The wcsrtombs() also sets errno to indicate the error.
The wcsrtombs() may causes an error in the following case:
[EILSEQ] pwcs points the string containing invalid wide character.
setlocale(3), wcrtomb(3), wcstombs(3)
The wcsrtombs() function conforms to ANSI X3.159-1989 (``ANSI C''). The
restrict qualifier is added at .
BSD February 4, 2002 BSD
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