wcsrtombs(3) Library Functions Manual wcsrtombs(3)
NAME
wcsrtombs - convert a wide-character string to a multibyte string
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <wchar.h>
size_t wcsrtombs(char dest[restrict .len], const wchar_t **restrict src,
size_t len, mbstate_t *restrict ps);
DESCRIPTION
If dest is not NULL, the wcsrtombs() function converts the wide-charac-
ter string *src to a multibyte string starting at dest. At most len
bytes are written to dest. The shift state *ps is updated. The con-
version 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:
• 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.
• 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.
• The wide-character string has been completely converted, including
the terminating null wide character (L'\0'), which has the side ef-
fect of bringing back *ps to the initial state. In this case, *src
is set to NULL, and the number of bytes written to dest, excluding
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 NULL, 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.
RETURN VALUE
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 con-
verted, (size_t) -1 is returned, and errno set to EILSEQ.
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
┌────────────┬───────────────┬─────────────────────────────────────────┐
│Interface │ Attribute │ Value │
├────────────┼───────────────┼─────────────────────────────────────────┤
│wcsrtombs() │ Thread safety │ MT-Unsafe race:wcsrtombs/!ps │
└────────────┴───────────────┴─────────────────────────────────────────┘
STANDARDS
POSIX.1-2001, POSIX.1-2008, C99.
NOTES
The behavior of wcsrtombs() depends on the LC_CTYPE category of the
current locale.
Passing NULL as ps is not multithread safe.
SEE ALSO
iconv(3), mbsinit(3), wcrtomb(3), wcsnrtombs(3), wcstombs(3)
Linux man-pages 6.03 2023-02-05 wcsrtombs(3)
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