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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
       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.

RETURN VALUE

       mbsinit() returns nonzero if *ps is an initial state, or  if  ps  is  a
       null pointer.  Otherwise it returns 0.

CONFORMING TO

       C99.

NOTES

       The  behavior  of  mbsinit()  depends  on  the LC_CTYPE category of the
       current locale.

SEE ALSO

       mbsrtowcs(3), wcsrtombs(3)

COLOPHON

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