mbsnrtowcs - convert a multibyte string to a wide charac
ter string
SYNOPSIS
#include <wchar.h>
size_t mbsnrtowcs (wchar_t *dest, const char **src,
size_t nms, size_t len, mbstate_t *ps);
DESCRIPTION
The mbsnrtowcs function is like the mbsrtowcs function,
except that the number of bytes to be converted, starting
at *src, is limited to nms.
If dest is not a NULL pointer, the mbsnrtowcs function
converts at most nms bytes from the multibyte string *src
to a wide-character string starting at dest. At most len
wide characters are written to dest. The shift state *ps
is updated. The conversion is effectively performed by
repeatedly calling mbrtowc(dest,*src,n,ps) where n is some
positive number, as long as this call succeeds, and then
incrementing dest by one and *src by the number of bytes
consumed. The conversion can stop for three reasons:
1. An invalid multibyte sequence has been encountered. In
this case *src is left pointing to the invalid multibyte
sequence, (size_t)(-1) is returned, and errno is set to
EILSEQ.
2. The nms limit forces a stop, or len non-L'\0' wide
characters have been stored at dest. In this case *src is
left pointing to the next multibyte sequence to be con
verted, and the number of wide characters written to dest
is returned.
3. The multibyte string has been completely converted,
including the terminating '\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 wide characters
written to dest, excluding the terminating L'\0' charac
ter, is returned.
If dest is NULL, len is ignored, and the conversion pro
ceeds as above, except that the converted wide characters
are not written out to memory, and that no destination
length limit exists.
In both of the above cases, if ps is a NULL pointer, a
static anonymous state only known to the mbsnrtowcs func
tion is used instead.
The programmer must ensure that there is room for at least
len wide characters at dest.
The mbsnrtowcs function returns the number of wide charac
ters that make up the converted part of the wide character
string, not including the terminating null wide character.
If an invalid multibyte sequence was encountered,
(size_t)(-1) is returned, and errno set to EILSEQ.
CONFORMING TO
This function is a GNU extension.
SEE ALSO
mbsrtowcs(3), iconv(3)
NOTES
The behaviour of mbsnrtowcs depends on the LC_CTYPE cate
gory of the current locale.
Passing NULL as ps is not multi-thread safe.
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