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WCSRTOMBS(3)               Library Functions Manual               WCSRTOMBS(3)

NAME
     wcsrtombs, wcsnrtombs - converts a wide-character string to a multibyte
     character string (restartable)

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <wchar.h>

     size_t
     wcsrtombs(char * restrict s, const wchar_t ** restrict pwcs, size_t n,
         mbstate_t * restrict ps);

     size_t
     wcsnrtombs(char * restrict s, const wchar_t ** restrict pwcs, size_t nwc,
         size_t n, mbstate_t * restrict ps);

DESCRIPTION
     The wcsrtombs() function converts the NUL-terminated wide-character
     string indirectly pointed to by pwcs to the corresponding multibyte
     character string, and stores it in the array pointed to by s.  The
     conversion stops due to the following reasons:

     ⊕   The conversion reaches a NUL wide character.  In this case, the NUL
         wide character is also converted.

     ⊕   The wcsrtombs() has already stored n bytes in the array pointed to by
         s.

     ⊕   The conversion encounters an invalid character.

     Each character will be converted as if wcrtomb(3) is continuously called,
     except the internal state of wcrtomb(3) will not be affected.

     After conversion, if s is not a NULL pointer, the pointer object pointed
     to by pwcs is a NULL pointer (if the conversion is stopped due to
     reaching a NUL wide character) or points to the first byte of the
     character just after the last character converted.

     If s is not a NULL pointer and the conversion is stopped due to reaching
     a NUL wide character, wcsrtombs() places the state object pointed to by
     ps to an initial state after the conversion is taken place.

     The behavior of wcsrtombs() is affected by the LC_CTYPE category of the
     current locale.

     These are the special cases:

     s == NULL         wcsrtombs() returns the number of bytes to store the
                       whole multibyte character string corresponding to the
                       wide-character string pointed to by pwcs, not including
                       the terminating NUL byte.  In this case, n is ignored.

     pwcs == NULL || *pwcs == NULL
                       Undefined (may cause the program to crash).

     ps == NULL        wcsrtombs() uses its own internal state object to keep
                       the conversion state, instead of ps mentioned in this
                       manual page.

                       Calling any other functions in Standard C Library
                       (libc, -lc) never changes the internal state of
                       wcsrtombs(), which is initialized at startup time of
                       the program.

     The wcsnrtombs() function behaves identically to wcsrtombs(), except that
     the conversion stops after reading at most nwc characters from the buffer
     pointed to by pwcs.

RETURN VALUES
     The wcsrtombs() and wcsnrtombs() functions return:

     0, or positive    Number of bytes stored in the array pointed to by s,
                       except for a NUL byte.  There are no cases that the
                       value returned is greater than n (unless s is a NULL
                       pointer).  If the return value is equal to n, the
                       string pointed to by s will not be NUL-terminated.

     (size_t)-1        pwcs points to a string containing an invalid wide
                       character.  The wcsrtombs() also sets errno to indicate
                       the error.

ERRORS
     The wcsrtombs() and wcsnrtombs() functions may fail with the following
     errors:

     [EILSEQ]           pwcs points to a string containing an invalid wide
                        character.

     [EINVAL]           ps points to an invalid or uninitialized mbstate_t
                        object.

SEE ALSO
     setlocale(3), wcrtomb(3), wcstombs(3)

STANDARDS
     The wcsrtombs() function conforms to ANSI X3.159-1989 ("ANSI C89").  The
     restrict qualifier was added by ISO/IEC 9899:1999 ("ISO C99").

     The wcsnrtombs() function conforms to IEEE Std 1003.1-2008 ("POSIX.1").

NetBSD 11.99                   October 13, 2024                   NetBSD 11.99