mbsinit

MBSINIT(3)                 Linux Programmer's Manual                MBSINIT(3)

NAME
       mbsinit - test for initial shift state

SYNOPSIS
       #include <wchar.h>

       int mbsinit(const mbstate_t *ps);

DESCRIPTION
       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 inter-
       rupted 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 wcsr-
       tombs(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 char-
       acter 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.

RETURN VALUE
       mbsinit() returns nonzero if *ps is an initial state, or if ps is NULL.
       Otherwise, it returns 0.

ATTRIBUTES
       For  an  explanation  of  the  terms  used  in  this  section,  see at-
       tributes(7).

       +----------+---------------+---------+
       |Interface | Attribute     | Value   |
       +----------+---------------+---------+
       |mbsinit() | Thread safety | MT-Safe |
       +----------+---------------+---------+
CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, C99.

NOTES
       The behavior of mbsinit() depends on the LC_CTYPE category of the  cur-
       rent locale.

SEE ALSO
       mbrlen(3), mbrtowc(3), mbsrtowcs(3), wcrtomb(3), wcsrtombs(3)

COLOPHON
       This  page  is  part of release 5.05 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                               2016-10-08                        MBSINIT(3)