ultrix man page for 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 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 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
       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.

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 attributes(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 current locale.

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

COLOPHON
       This page is part of release 4.15 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)