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.TH MBSINIT 3  2016-10-08 "GNU" "Linux Programmer's Manual"

.SH NAME

mbsinit \- test for initial shift state

.SH SYNOPSIS

.nf

.B #include <wchar.h>

.PP

.BI "int mbsinit(const mbstate_t *" ps );

.fi

.SH DESCRIPTION

Character conversion between the multibyte representation and the wide

character representation uses conversion state, of type

.IR 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.

.PP

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

.BR mbsrtowcs (3),

and the one used by wide

character to multibyte conversion functions, such as

.BR wcsrtombs (3),

but they both fit in a

.IR mbstate_t ,

and they both have the same

representation for an initial state.

.PP

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

.BR mbrtowc (3)

do

produce non-initial states when interrupted in the middle of a character.

.PP

One possible way to create an

.I mbstate_t

in initial state is to set it to zero:

.PP

.in +4n

.EX

mbstate_t state;

memset(&state,0,sizeof(mbstate_t));

.EE

.in

.PP

On Linux, the following works as well, but might generate compiler warnings:

.PP

.in +4n

.EX

mbstate_t state = { 0 };

.EE

.in

.PP

The function

.BR mbsinit ()

tests whether

.I *ps

corresponds to an

initial state.

.SH RETURN VALUE

.BR mbsinit ()

returns nonzero if

.I *ps

is an initial state, or if

.I ps

is NULL.

Otherwise, it returns 0.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lb lb lb

l l l.

Interface	Attribute	Value

T{

.BR mbsinit ()

T}	Thread safety	MT-Safe

.TE

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008, C99.

.SH NOTES

The behavior of

.BR mbsinit ()

depends on the

.B LC_CTYPE

category of the

current locale.

.SH SEE ALSO

.BR mbrlen (3),

.BR mbrtowc (3),

.BR mbsrtowcs (3),

.BR wcrtomb (3),

.BR wcsrtombs (3)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I 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/.