MBRTOWC(3)

NAME
mbrtowc - convert a multibyte sequence to a wide character

SYNOPSIS
#include <wchar.h>

size_t mbrtowc (wchar_t* pwc, const char* s, size_t n, mbstate_t* ps);

DESCRIPTION
The main case for this function is when s is not NULL and pwc is not NULL. In this case, the mbrtowc function inspects at most n bytes of the multibyte string starting at s, extracts the next complete multibyte character, converts it to a wide character and stores it at *pwc. It updates the shift state *ps. If the converted wide character is not L'\0', it returns the number of bytes that were consumed from s. If the converted wide character is L'\0', it resets the shift state *ps to the initial state and returns 0.

If the n bytes starting at s do not contain a complete multibyte character, mbrtowc keeps track of the partial multibyte character by updating *ps and returns (size_t)(-2). This can happen even if n >= MB_CUR_MAX, if the multibyte string contains redundant shift sequences.

If the multibyte string starting at s contains an invalid multibyte sequence before the next complete character, mbrtowc returns (size_t)(-1) and sets errno to EILSEQ. In this case, the effects on *ps are undefined.

A different case is when s is not NULL but pwc is NULL. In this case the mbrtowc function behaves as above, excepts that it does not store the converted wide character in memory.

A third case is when s is NULL. In this case, pwc and n are ignored. If *ps contains no partially accumulated multibyte character, the mbrtowc function puts *ps in the initial state and returns 0; otherwise it returns (size_t)(-1) and sets errno to EILSEQ.

In all of the above cases, if ps is a NULL pointer, a static anonymous state only known to the mbrtowc function is used instead.

RETURN VALUE
The mbrtowc function returns the number of bytes parsed from the multibyte sequence starting at s, if a non-L'\0' wide character was recognized. It returns 0, if a L'\0' wide character was recognized. It returns (size_t)(-1) and sets errno to EILSEQ, if an invalid multibyte sequence was encountered. It returns (size_t)(-2) if it couldn't parse a complete multibyte character, meaning that the remaining bytes should be fed to mbrtowc in a new call.

CONFORMING TO
ISO/ANSI C, UNIX98

SEE ALSO
mbsrtowcs(3)

NOTES
The behaviour of mbrtowc depends on the LC_CTYPE category of the current locale.