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iconv — perform character set conversion
#include <iconv.h>
size_t
iconv( |
iconv_t cd, |
| char **inbuf, | |
| size_t *inbytesleft, | |
| char **outbuf, | |
size_t *outbytesleft); |
The iconv() function
converts a sequence of characters in one character encoding
to a sequence of characters in another character encoding.
The cd argument is a
conversion descriptor, previously created by a call to
iconv_open(3); the
conversion descriptor defines the character encodings that
iconv() uses for the
conversion. The inbuf
argument is the address of a variable that points to the
first character of the input sequence; inbytesleft indicates the
number of bytes in that buffer. The outbuf argument is the address
of a variable that points to the first byte available in the
output buffer; outbytesleft indicates the
number of bytes available in the output buffer.
The main case is when inbuf is not NULL and
*inbuf is not NULL.
In this case, the iconv()
function converts the multibyte sequence starting at
*inbuf to a multibyte
sequence starting at *outbuf. At most *inbytesleft bytes, starting at
*inbuf, will be read.
At most *outbytesleft
bytes, starting at *outbuf, will be written.
The iconv() function
converts one multibyte character at a time, and for each
character conversion it increments *inbuf and decrements
*inbytesleft by the
number of converted input bytes, it increments *outbuf and decrements
*outbytesleft by the
number of converted output bytes, and it updates the
conversion state contained in cd. If the character encoding
of the input is stateful, the 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
shift sequence. The
conversion can stop for four reasons:
An invalid multibyte sequence is encountered in the
input. In this case it sets errno to EILSEQ and returns (size_t) −1.
*inbuf is left
pointing to the beginning of the invalid multibyte
sequence.
The input byte sequence has been entirely converted,
that is, *inbytesleft has gone down
to 0. In this case iconv() returns the number of
nonreversible conversions performed during this
call.
An incomplete multibyte sequence is encountered in
the input, and the input byte sequence terminates after
it. In this case it sets errno to EINVAL and returns (size_t) −1.
*inbuf is left
pointing to the beginning of the incomplete multibyte
sequence.
The output buffer has no more room for the next
converted character. In this case it sets errno to E2BIG and returns (size_t) −1.
A different case is when inbuf is NULL or *inbuf is NULL, but outbuf is not NULL and
*outbuf is not NULL.
In this case, the iconv()
function attempts to set cd's conversion state to the
initial state and store a corresponding shift sequence at
*outbuf. At most
*outbytesleft bytes,
starting at *outbuf,
will be written. If the output buffer has no more room for
this reset sequence, it sets errno to E2BIG and returns (size_t) −1. Otherwise it
increments *outbuf
and decrements *outbytesleft by the number of
bytes written.
A third case is when inbuf is NULL or *inbuf is NULL, and outbuf is NULL or *outbuf is NULL. In this case,
the iconv() function sets
cd's conversion state
to the initial state.
The 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 errno and
returns (size_t)
−1.
The following errors can occur, among others:
There is not sufficient room at *outbuf.
An invalid multibyte sequence has been encountered in the input.
An incomplete multibyte sequence has been encountered in the input.
Although inbuf and
outbuf are typed as
char **, this does not
mean that the objects they point can be interpreted as C
strings or as arrays of characters: the interpretation of
character byte sequences is handled internally by the
conversion functions. In some encodings, a zero byte may be a
valid part of a multibyte character.
The caller of iconv() must
ensure that the pointers passed to the function are suitable
for accessing characters in the appropriate character set.
This includes ensuring correct alignment on platforms that
have tight restrictions on alignment.
This page is part of release 3.52 of the Linux man-pages project. A
description of the project, and information about reporting
bugs, can be found at
http://www.kernel.org/doc/man−pages/.
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Copyright (c) Bruno Haible <haibleclisp.cons.org> %%%LICENSE_START(GPLv2+_DOC_ONEPARA) This is free documentation; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. %%%LICENSE_END References consulted: GNU glibc-2 source code and manual OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html 2000-06-30 correction by Yuichi SATO <satocomplex.eng.hokudai.ac.jp> 2000-11-15 aeb, fixed prototype |