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, con
verts it to a wide character and stores it at *pwc. It
updates the shift state *ps. If the converted wide charac
ter 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 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. 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.
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 n should be
increased.
ISO/ANSI C, UNIX98
SEE ALSO
mbsrtowcs(3)
NOTES
The behaviour of mbrtowc depends on the LC_CTYPE category
of the current locale.
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