MBRTOWC(3)

NAME
mbrtowc, mbrtowc_l, mbrtoc16, mbrtoc16_l, mbrtoc32, mbrtoc32_l - convert a character to a wide-character code (restartable)

LIBRARY
libc

SYNOPSIS
#include <wchar.h>
size_t
mbrtowc(wchar_t * restrict pc, const char * restrict s, size_t n, mbstate_t * restrict ps);
#include <uchar.h>
size_t
mbrtoc16(char16_t * restrict pc, const char * restrict s, size_t n, mbstate_t * restrict ps);
size_t
mbrtoc32(char32_t * restrict pc, const char * restrict s, size_t n, mbstate_t * restrict ps);
#include <xlocale.h>
size_t
mbrtowc_l(wchar_t * restrict pc, const char * restrict s, size_t n, mbstate_t * restrict ps, locale_t locale);
size_t
mbrtoc16_l(char16_t * restrict pc, const char * restrict s, size_t n, mbstate_t * restrict ps, locale_t locale);
size_t
mbrtoc32_l(char32_t * restrict pc, const char * restrict s, size_t n, mbstate_t * restrict ps, locale_t locale);

DESCRIPTION
The mbrtowc(), mbrtowc_l(), mbrtoc16(), mbrtoc16_l(), mbrtoc32(), and mbrtoc32_l() functions inspect at most n bytes pointed to by s to determine the number of bytes needed to complete the next multibyte character. If a character can be completed, and pc is not NULL, the wide character which is represented by s is stored in the wchar_t, char16_t or char32_t it points to.

If s is NULL, these functions behave as if pc was NULL, s was an empty string ("") and n was 1.

The mbstate_t argument, ps, is used to keep track of the shift state. If it is NULL, these functions use an internal, static mbstate_t object, which is initialized to the initial conversion state at program startup.

As a single char16_t is not large enough to represent certain multibyte characters, the mbrtoc16() function may need to be invoked multiple times to convert a single multibyte character sequence.

The mbrtowc_l(), mbrtoc16_l(), and mbrtoc32_l() functions take an explicit locale argument, whereas the mbrtowc(), mbrtoc16(), and mbrtoc32() functions use the current global or per-thread locale.

RETURN VALUES
The mbrtowc(), mbrtowc_l(), mbrtoc16(), mbrtoc16_l(), mbrtoc32(), and mbrtoc32_l() functions return:

0   The next n or fewer bytes represent the null wide character (L'\0').

>0  The next n or fewer bytes represent a valid character, these functions return the number of bytes used to complete the multibyte character.

(size_t)-1
    An encoding error has occurred. The next n or fewer bytes do not contribute to a valid multibyte character.

(size_t)-2
    The next n contribute to, but do not complete, a valid multibyte character sequence, and all n bytes have been processed.

The mbrtoc16() and mbrtoc16_l() functions also return:

(size_t)-3
    The next character resulting from a previous call has been stored. No bytes from the input have been consumed.

ERRORS
The mbrtowc(), mbrtowc_l(), mbrtoc16(), mbrtoc16_l(), mbrtoc32(), and mbrtoc32_l() functions will fail if:

[EILSEQ]
    An invalid multibyte sequence was detected.

[EINVAL]
    The conversion state is invalid.

SEE ALSO
mbtowc(3), multibyte(3), setlocale(3), wcrtomb(3), xlocale(3)

STANDARDS
The mbrtowc(), mbrtoc16() and mbrtoc32() functions conform to isoC-2011.