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NAME
mbsrtowcs - convert a multibyte string to a wide-character string
SYNOPSIS
#include <wchar.h> size_t mbsrtowcs(wchar_t *dest, const char **src, size_t len, mbstate_t *ps);
DESCRIPTION
If dest is not a NULL pointer, the mbsrtowcs() function converts 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. 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 converted, and the number of wide characters written to dest is
returned.
3. The multibyte string has been completely converted, including the terminating null wide character
('\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 null wide
character, is returned.
If dest is NULL, len is ignored, and the conversion proceeds as above, except that the converted wide
characters 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
mbsrtowcs() function is used instead.
The programmer must ensure that there is room for at least len wide characters at dest.
RETURN VALUE
The mbsrtowcs() function returns the number of wide characters 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
C99.
NOTES
The behavior of mbsrtowcs() depends on the LC_CTYPE category of the current locale.
Passing NULL as ps is not multithread safe.
SEE ALSO
iconv(3), mbsnrtowcs(3), mbstowcs(3)
COLOPHON
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