MBTOWC(3) Linux Programmer's Manual MBTOWC(3)
mbtowc - convert a multibyte sequence to a wide character
int mbtowc(wchar_t *pwc, const char *s, size_t n);
The main case for this function is when s is not NULL and pwc is not NULL. In this case,
the mbtowc() 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 an internal shift state known only to the mbtowc() function. If s
does not point to a null byte ('\0'), it returns the number of bytes that were consumed
from s, otherwise it returns 0.
If the n bytes starting at s do not contain a complete multibyte character, or if they
contain an invalid multibyte sequence, mbtowc() returns -1. This can happen even if n >=
MB_CUR_MAX, if the multibyte string contains redundant shift sequences.
A different case is when s is not NULL but pwc is NULL. In this case the mbtowc() func-
tion behaves as above, except that it does not store the converted wide character in mem-
A third case is when s is NULL. In this case, pwc and n are ignored. The mbtowc() func-
tion resets the shift state, only known to this function, to the initial state, and
returns nonzero if the encoding has nontrivial shift state, or zero if the encoding is
If s is not NULL, the mbtowc() function returns the number of consumed bytes starting at
s, or 0 if s points to a null byte, or -1 upon failure.
If s is NULL, the mbtowc() function returns nonzero if the encoding has nontrivial shift
state, or zero if the encoding is stateless.
The behavior of mbtowc() depends on the LC_CTYPE category of the current locale.
This function is not multithread safe. The function mbrtowc(3) provides a better inter-
face to the same functionality.
MB_CUR_MAX(3), mbrtowc(3), mbstowcs(3)
This page is part of release 3.55 of the Linux man-pages project. A description of the
project, and information about reporting bugs, can be found at
GNU 2011-09-28 MBTOWC(3)