MBRTOWC(3) Linux Programmer's Manual 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' ' (the null wide character), it returns the number of
bytes that were consumed from s. If the converted wide character is L' ', 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() 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, 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
multibyte 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 NULL, a static anonymous state known only 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));
RETURN VALUE
The mbrtowc() function returns the number of bytes parsed from the multibyte sequence starting at s, if a non-L' ' wide character was rec-
ognized. It returns 0, if a L' ' 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 n should be increased.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
+----------+---------------+----------------------------+
|Interface | Attribute | Value |
+----------+---------------+----------------------------+
|mbrtowc() | Thread safety | MT-Unsafe race:mbrtowc/!ps |
+----------+---------------+----------------------------+
CONFORMING TO
POSIX.1-2001, POSIX.1-2008, C99.
NOTES
The behavior of mbrtowc() depends on the LC_CTYPE category of the current locale.
SEE ALSO
mbsinit(3), mbsrtowcs(3)
COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the
latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
GNU
2015-08-08 MBRTOWC(3)
