mbsinit - test for initial shift state
#include <wchar.h>
int mbsinit(const mbstate_t *ps);
Character conversion between the multibyte representation and the wide character
representation uses conversion state, of type
mbstate_t. Conversion of
a string uses a finite-state machine; when it is interrupted after the
complete conversion of a number of characters, it may need to save a state for
processing the remaining characters. Such a conversion state is needed for the
sake of encodings such as ISO-2022 and UTF-7.
The initial state is the state at the beginning of conversion of a string. There
are two kinds of state: the one used by multibyte to wide character conversion
functions, such as
mbsrtowcs(3), and the one used by wide character to
multibyte conversion functions, such as
wcsrtombs(3), but they both fit
in a
mbstate_t, and they both have the same representation for an
initial state.
For 8-bit encodings, all states are equivalent to the initial state. For
multibyte encodings like UTF-8, EUC-*, BIG5 or SJIS, the wide character to
multibyte conversion functions never produce non-initial states, but the
multibyte to wide-character conversion functions like
mbrtowc(3) do
produce non-initial states when interrupted in the middle of a character.
One possible way to create an
mbstate_t in initial state is to set it to
zero:
mbstate_t state;
memset(&state,0,sizeof(mbstate_t));
On Linux, the following works as well, but might generate compiler warnings:
mbstate_t state = { 0 };
The function
mbsinit() tests whether
*ps corresponds to an initial
state.
mbsinit() returns nonzero if
*ps is an initial state, or if
ps is NULL. Otherwise, it returns 0.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| mbsinit () |
Thread safety |
MT-Safe |
POSIX.1-2001, POSIX.1-2008, C99.
The behavior of
mbsinit() depends on the
LC_CTYPE category of the
current locale.
mbrlen(3),
mbrtowc(3),
mbsrtowcs(3),
wcrtomb(3),
wcsrtombs(3)