mbsnrtowcs(3) Library Functions Manual mbsnrtowcs(3)
NAME
mbsnrtowcs - convert a multibyte string to a wide-character string
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <wchar.h>
size_t mbsnrtowcs(wchar_t dest[restrict .len], const char **restrict src,
size_t nms, size_t len, mbstate_t *restrict ps);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
mbsnrtowcs():
Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
_GNU_SOURCE
DESCRIPTION
The mbsnrtowcs() function is like the mbsrtowcs(3) function, except that
the number of bytes to be converted, starting at *src, is limited to at
most nms bytes.
If dest is not NULL, 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 re-
peatedly 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:
• 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.
• 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 converted, and the number of wide characters
written to dest is returned.
• 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.
According to POSIX.1, if the input buffer ends with an incomplete char-
acter, it is unspecified whether conversion stops at the end of the pre-
vious character (if any), or at the end of the input buffer. The glibc
implementation adopts the former behavior.
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 destination length limit exists.
In both of the above cases, if ps is NULL, a static anonymous state
known only to the mbsnrtowcs() function is used instead.
The programmer must ensure that there is room for at least len wide
characters at dest.
RETURN VALUE
The mbsnrtowcs() 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.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
┌──────────────┬───────────────┬───────────────────────────────────────┐
│ Interface │ Attribute │ Value │
├──────────────┼───────────────┼───────────────────────────────────────┤
│ mbsnrtowcs() │ Thread safety │ MT-Unsafe race:mbsnrtowcs/!ps │
└──────────────┴───────────────┴───────────────────────────────────────┘
STANDARDS
POSIX.1-2008.
NOTES
The behavior of mbsnrtowcs() depends on the LC_CTYPE category of the
current locale.
Passing NULL as ps is not multithread safe.
SEE ALSO
iconv(3), mbrtowc(3), mbsinit(3), mbsrtowcs(3)
Linux man-pages 6.9.1 2024-06-15 mbsnrtowcs(3)
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