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, and the one
       used by wide character to multibyte conversion functions, such as wcsr-
       tombs,  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 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 non-zero if *ps is an initial state, or if ps is a null
       pointer. Otherwise it returns 0.

CONFORMING TO
       ISO/ANSI C, UNIX98

SEE ALSO
       mbsrtowcs(3), wcsrtombs(3)

NOTES
       The  behaviour  of mbsinit depends on the LC_CTYPE category of the cur-
       rent locale.



GNU                               2000-11-20                        MBSINIT(3)