wcsrtombs(3) — Linux manual page


wcsrtombs(3)            Library Functions Manual            wcsrtombs(3)

NAME         top

       wcsrtombs - convert a wide-character string to a multibyte string

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <wchar.h>

       size_t wcsrtombs(char dest[restrict .len], const wchar_t **restrict src,
                        size_t len, mbstate_t *restrict ps);

DESCRIPTION         top

       If dest is not NULL, 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:

       •  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

       •  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 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, 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         top

       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

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       │ Interface   Attribute     Value                           │
       │ wcsrtombs() │ Thread safety │ MT-Unsafe race:wcsrtombs/!ps    │

STANDARDS         top

       C11, POSIX.1-2008.

HISTORY         top

       POSIX.1-2001, C99.

NOTES         top

       The behavior of wcsrtombs() depends on the LC_CTYPE category of
       the current locale.

       Passing NULL as ps is not multithread safe.

SEE ALSO         top

       iconv(3), mbsinit(3), wcrtomb(3), wcsnrtombs(3), wcstombs(3)

Linux man-pages (unreleased)   2024-05-02                   wcsrtombs(3)

Pages that refer to this page: mbsinit(3)mbstate_t(3type)wcrtomb(3)wcsnrtombs(3)wcstombs(3)