MBRTOWC(3) Linux Programmer's Manual MBRTOWC(3)
mbrtowc - convert a multibyte sequence to a wide character
size_t mbrtowc(wchar_t *pwc, const char *s, size_t n, mbstate_t *ps);
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 multi-
byte 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 char-
acter, mbrtowc() 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
A different case is when s is not NULL but pwc is NULL. In this case
the mbrtowc() function behaves as above, except 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 the conversion state represented by *ps denotes an incomplete multi-
byte character conversion, the mbrtowc() function returns (size_t) -1,
sets errno to EILSEQ, and leaves *ps in an undefined state. Otherwise,
the mbrtowc() function puts *ps in the initial state and returns 0.
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. Otherwise,
*ps must be a valid mbstate_t object. An mbstate_t object a can be
initialized to the initial state by zeroing it, for example using
memset(&a, 0, sizeof(a));
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 multi-
byte sequence was encountered. It returns (size_t) -2 if it couldn't
parse a complete multibyte character, meaning that n should be
The behavior of mbrtowc() depends on the LC_CTYPE category of the cur-
This page is part of release 3.05 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2001-11-22 MBRTOWC(3)