| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | CONFORMING TO | NOTES | SEE ALSO | COLOPHON | The Linux Programming Interface |
MBRTOWC(3) Linux Programmer's Manual MBRTOWC(3)
mbrtowc - convert a multibyte sequence to a wide character
#include <wchar.h>
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 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() 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 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 multibyte sequence was encountered.
It returns (size_t) -2 if it couldn't parse a complete multibyte character,
meaning that n should be increased.
C99.
The behavior of mbrtowc() depends on the LC_CTYPE category of the current
locale.
mbsrtowcs(3)
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GNU 2001-11-22 MBRTOWC(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface