WCSRTOMBS(3)

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

SYNOPSIS
#include <stdlib.h>
size_t
wcsrtombs(const char * restrict s, const wchar_t ** restrict pwcs, size_t n, mbstate_t * restrict ps);

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

•   The conversion reaches a null wide character. In this case, the null wide character is also converted.

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

•   The conversion encounters an invalid character.

Each characters 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 null wide character) or 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 null wide character, the wcsrtombs() places the state object pointed to by ps to an initial state after the conversion is taken place.

The behaviour of the 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 null byte. In this case, n is ignored.

pwcs == NULL || *pwcs == NULL
    Undefined (may causes 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 libc never change the internal state of wcsrtombs(), that is initialized at startup time of the program.

RETURN VALUES
wcsrtombs() returns:

0 or positive
    Number of bytes stored to the array pointed to by s, except for a null byte. There is 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 null-terminated.

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

ERRORS
wcsrtombs() may cause an error in the following cases:

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

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

STANDARDS
The wcsrtombs() function conforms to ansiC. The restrict qualifier is added at ISO/IEC 9899/AMD1:1995 (“ISO C99”).