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-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 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 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

       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
       EILSEQ.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────┬───────────────┬────────────────────────────────────────────────────────────┐
       │Interface   │ Attribute     │ Value                                                      │
       ├────────────┼───────────────┼────────────────────────────────────────────────────────────┤
       │wcsrtombs() │ Thread safety │ MT-Unsafe race:wcsrtombs/!ps                               │
       └────────────┴───────────────┴────────────────────────────────────────────────────────────┘

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       POSIX.1-2001, 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)