man-pages/man3/mbrlen.3

.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
.\"
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.\" References consulted:
.\"   GNU glibc-2 source code and manual
.\"   Dinkumware C library reference http://www.dinkumware.com/
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.\"   ISO/IEC 9899:1999
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.TH MBRLEN 3  1999-07-25 "GNU" "Linux Programmer's Manual"
.SH NAME
mbrlen \- determine number of bytes in next multibyte character
.SH SYNOPSIS
.nf
.B #include <wchar.h>
.sp
.BI "size_t mbrlen(const char *" s ", size_t " n ", mbstate_t *" ps );
.fi
.SH DESCRIPTION
The
.BR mbrlen ()
function inspects at most \fIn\fP bytes of the multibyte
string starting at \fIs\fP and extracts the next complete multibyte character.
It updates the shift state \fI*ps\fP.
If the multibyte character is not the
null wide character, it returns the number of bytes that were consumed from
\fIs\fP.
If the multibyte character is the null wide character, it resets the
shift state \fI*ps\fP to the initial state and returns 0.
.PP
If the \fIn\fP bytes starting at \fIs\fP do not contain a complete multibyte
character,
.BR mbrlen ()
returns \fI(size_t)(\-2)\fP.
This can happen even if
\fIn\fP >= \fIMB_CUR_MAX\fP, if the multibyte string contains redundant shift
sequences.
.PP
If the multibyte string starting at \fIs\fP contains an invalid multibyte
sequence before the next complete character,
.BR mbrlen ()
returns
\fI(size_t)(\-1)\fP and sets \fIerrno\fP to \fBEILSEQ\fP.
In this case,
the effects on \fI*ps\fP are undefined.
.PP
If \fIps\fP is a NULL pointer, a static anonymous state only known to the
mbrlen function is used instead.
.SH "RETURN VALUE"
The
.BR mbrlen ()
function returns the number of bytes
parsed from the multibyte
sequence starting at \fIs\fP, if a non-null wide character was recognized.
It returns 0, if a null wide character was recognized.
It returns (size_t)(\-1)
and sets \fIerrno\fP to \fBEILSEQ\fP, if an invalid multibyte sequence was
encountered.
It returns (size_t)(\-2) if it couldn't parse a complete multibyte
character, meaning that \fIn\fP should be increased.
.SH "CONFORMING TO"
C99
.SH NOTES
The behaviour of
.BR mbrlen ()
depends on the LC_CTYPE category of the
current locale.
.SH "SEE ALSO"
.BR mbrtowc (3)