WCSRTOMBS(3) Linux Programmer's Manual WCSRTOMBS(3)
wcsrtombs - convert a wide-character string to a multibyte string
size_t wcsrtombs(char *dest, const wchar_t **src,
size_t len, mbstate_t *ps);
If dest is not a NULL pointer, the wcsrtombs() function converts the wide-character string
*src to a multibyte string starting at dest. At most len bytes are written to dest. The
shift state *ps is updated. The conversion is effectively performed by repeatedly calling
wcrtomb(dest, *src, ps), as long as this call succeeds, and then incrementing dest by the
number of bytes written and *src by one. The conversion can stop for three reasons:
1. A wide character has been encountered that can not be represented as a multibyte
sequence (according to the current locale). In this case *src is left pointing to the
invalid wide character, (size_t) -1 is returned, and errno is set to EILSEQ.
2. The length limit forces a stop. In this case *src is left pointing to the next wide
character to be converted, and the number of bytes written to dest is returned.
3. The wide-character string has been completely converted, including the terminating null
wide character (L'\0'), which has the side effect of bringing back *ps to the initial
state. In this case *src is set to NULL, and the number of bytes written to dest, exclud-
ing the terminating null byte ('\0'), is returned.
If dest is NULL, len is ignored, and the conversion proceeds as above, except that the
converted bytes are not written out to memory, and that no length limit exists.
In both of the above cases, if ps is a NULL pointer, a static anonymous state known only
to the wcsrtombs() function is used instead.
The programmer must ensure that there is room for at least len bytes at dest.
The wcsrtombs() function returns the number of bytes that make up the converted part of
multibyte sequence, not including the terminating null byte. If a wide character was
encountered which could not be converted, (size_t) -1 is returned, and errno set to
The behavior of wcsrtombs() depends on the LC_CTYPE category of the current locale.
Passing NULL as ps is not multithread safe.
iconv(3), wcsnrtombs(3), wcstombs(3)
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GNU 2011-10-16 WCSRTOMBS(3)