.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
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.\" 2000-06-30 correction by Yuichi SATO <sato@complex.eng.hokudai.ac.jp>
.\" 2000-11-15 aeb, fixed prototype
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.TH ICONV 3 2008-09-08 "GNU" "Linux Programmer's Manual"
.SH NAME
iconv \- perform character set conversion
.SH SYNOPSIS
.nf
.B #include <iconv.h>
.sp
.BI "size_t iconv(iconv_t " cd ,
.BI "             char **" inbuf ", size_t *" inbytesleft ,
.BI "             char **" outbuf ", size_t *" outbytesleft );
.fi
.SH DESCRIPTION
The argument \fIcd\fP must be a conversion descriptor created using the
function
.BR iconv_open (3).
.PP
The main case is when \fIinbuf\fP is not NULL and \fI*inbuf\fP is not NULL.
In this case, the
.BR iconv ()
function converts the multibyte sequence
starting at \fI*inbuf\fP to a multibyte sequence starting at \fI*outbuf\fP.
At most \fI*inbytesleft\fP bytes, starting at \fI*inbuf\fP, will be read.
At most \fI*outbytesleft\fP bytes, starting at \fI*outbuf\fP, will be written.
.PP
The
.BR iconv ()
function converts one multibyte character at a time, and for
each character conversion it increments \fI*inbuf\fP and decrements
\fI*inbytesleft\fP by the number of converted input bytes, it increments
\fI*outbuf\fP and decrements \fI*outbytesleft\fP by the number of converted
output bytes, and it updates the conversion state contained in \fIcd\fP.
If the character encoding of the input is stateful, the
.BR iconv ()
function can also convert a sequence of input bytes
to an update to the conversion state without producing any output bytes;
such input is called a \fIshift sequence\fP.
The conversion can stop for four reasons:
.PP
1. An invalid multibyte sequence is encountered in the input.
In this case
it sets \fIerrno\fP to \fBEILSEQ\fP and returns
.IR (size_t)\ \-1 .
\fI*inbuf\fP
is left pointing to the beginning of the invalid multibyte sequence.
.PP
2. The input byte sequence has been entirely converted,
that is, \fI*inbytesleft\fP has gone down to 0.
In this case
.BR iconv ()
returns the number of
nonreversible conversions performed during this call.
.PP
3. An incomplete multibyte sequence is encountered in the input, and the
input byte sequence terminates after it.
In this case it sets \fIerrno\fP to
\fBEINVAL\fP and returns
.IR (size_t)\ \-1 .
\fI*inbuf\fP is left pointing to the
beginning of the incomplete multibyte sequence.
.PP
4. The output buffer has no more room for the next converted character.
In this case it sets \fIerrno\fP to \fBE2BIG\fP and returns
.IR (size_t)\ \-1 .
.PP
A different case is when \fIinbuf\fP is NULL or \fI*inbuf\fP is NULL, but
\fIoutbuf\fP is not NULL and \fI*outbuf\fP is not NULL.
In this case, the
.BR iconv ()
function attempts to set \fIcd\fP's conversion state to the
initial state and store a corresponding shift sequence at \fI*outbuf\fP.
At most \fI*outbytesleft\fP bytes, starting at \fI*outbuf\fP, will be written.
If the output buffer has no more room for this reset sequence, it sets
\fIerrno\fP to \fBE2BIG\fP and returns
.IR (size_t)\ \-1 .
Otherwise it increments
\fI*outbuf\fP and decrements \fI*outbytesleft\fP by the number of bytes
written.
.PP
A third case is when \fIinbuf\fP is NULL or \fI*inbuf\fP is NULL, and
\fIoutbuf\fP is NULL or \fI*outbuf\fP is NULL.
In this case, the
.BR iconv ()
function sets \fIcd\fP's conversion state to the initial state.
.SH CAVEAT
The type of
.I inbuf
and
.IR outbuf ", "
.BR "char **" ,
does not imply that the objects pointed to are interpreted as
null-terminated C strings or arrays of characters.
The caller of
.B iconv
has to make sure that the pointers passed to the function are suitable
for access of characters from the appropriate character set.
This includes alignment on platforms that have tight restriction on
alignment.
.SH "RETURN VALUE"
The
.BR iconv ()
function returns the number of characters converted in a
nonreversible way during this call; reversible conversions are not counted.
In case of error, it sets \fIerrno\fP and returns
.IR (size_t)\ \-1 .
.SH ERRORS
The following errors can occur, among others:
.TP
.B E2BIG
There is not sufficient room at \fI*outbuf\fP.
.TP
.B EILSEQ
An invalid multibyte sequence has been encountered in the input.
.TP
.B EINVAL
An incomplete multibyte sequence has been encountered in the input.
.SH VERSIONS
This function is available in glibc since version 2.1.
.SH "CONFORMING TO"
POSIX.1-2001.
.SH "SEE ALSO"
.BR iconv_close (3),
.BR iconv_open (3)
.SH COLOPHON
This page is part of release 3.28 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.