libiconv - GNU Project - Free Software Foundation (FSF)
libiconv
Introduction
Get the Software
Introduction to libiconv
International text is mostly encoded in
Unicode
For historical reasons, however, it is sometimes still encoded using a
language or country dependent character encoding. With the advent of the
internet and the frequent exchange of text across countries - even the
viewing of a web page from a foreign country is a "text exchange" in this
context -, conversions between these encodings have become a necessity.
In particular, computers with the Windows operating system still operate
in locale with a traditional (limited)
character encoding. Some programs, like mailers and web browsers, must
be able to convert between a given text encoding and the user's encoding.
Other programs internally store strings in Unicode, to facilitate internal
processing, and need to convert between internal string representation
(Unicode) and external string representation (a traditional encoding)
when they are doing I/O. GNU libiconv is a conversion library for both
kinds of applications.
Details
This library provides an
iconv()
implementation, for use on systems which
don't have one, or whose implementation cannot convert from/to Unicode.
It provides support for the encodings:
European languages
ASCII, ISO-8859-{1,2,3,4,5,7,9,10,13,14,15,16},
KOI8-R, KOI8-U, KOI8-RU,
CP{1250,1251,1252,1253,1254,1257}, CP{850,866,1131},
Mac{Roman,CentralEurope,Iceland,Croatian,Romania},
Mac{Cyrillic,Ukraine,Greek,Turkish},
Macintosh
Semitic languages
ISO-8859-{6,8}, CP{1255,1256}, CP862, Mac{Hebrew,Arabic}
Japanese
EUC-JP, SHIFT_JIS, CP932, ISO-2022-JP, ISO-2022-JP-2, ISO-2022-JP-1,
ISO-2022-JP-MS
Chinese
EUC-CN, HZ, GBK, CP936, GB18030, EUC-TW, BIG5, CP950, BIG5-HKSCS,
BIG5-HKSCS:2004, BIG5-HKSCS:2001, BIG5-HKSCS:1999, ISO-2022-CN,
ISO-2022-CN-EXT
Korean
EUC-KR, CP949, ISO-2022-KR, JOHAB
Armenian
ARMSCII-8
Georgian
Georgian-Academy, Georgian-PS
Tajik
KOI8-T
Kazakh
PT154, RK1048
Thai
ISO-8859-11, TIS-620, CP874, MacThai
Laotian
MuleLao-1, CP1133
Vietnamese
VISCII, TCVN, CP1258
Platform specifics
HP-ROMAN8, NEXTSTEP
Full Unicode
UTF-8
UCS-2, UCS-2BE, UCS-2LE
UCS-4, UCS-4BE, UCS-4LE
UTF-16, UTF-16BE, UTF-16LE
UTF-32, UTF-32BE, UTF-32LE
UTF-7
C99, JAVA
Full Unicode, in terms of
uint16_t
or
uint32_t
(with machine dependent endianness and alignment)
UCS-2-INTERNAL, UCS-4-INTERNAL
Locale dependent, in terms of `char' or `wchar_t'
(with machine dependent endianness and alignment, and with OS and
locale dependent semantics)
char, wchar_t
The empty encoding name "" is equivalent to "char": it denotes the
locale dependent character encoding.
When configured with the option
--enable-extra-encodings
, it also provides
support for a few extra encodings:
European languages
CP{437,737,775,852,853,855,857,858,860,861,863,865,869,1125}
Semitic languages
CP864
Japanese
EUC-JISX0213, Shift_JISX0213, ISO-2022-JP-3
Chinese
BIG5-2003 (experimental)
Turkmen
TDS565
Platform specifics
ATARIST, RISCOS-LATIN1
It can convert from any of these encodings to any other, through Unicode
conversion.
It has also some limited support for transliteration, i.e. when a character
cannot be represented in the target character set, it can be approximated
through one or several similarly looking characters. Transliteration is
activated when "//TRANSLIT" is appended to the target encoding name.
libiconv is for you if your application needs to support multiple character
encodings, but that support lacks from your system.
Installation
As usual for GNU packages:
$ ./configure --prefix=/usr/local
$ make
$ make install
After installing GNU libiconv for the first time, it is recommended to
recompile and reinstall GNU gettext, so that it can take advantage of
libiconv.
On systems other than GNU/Linux, the iconv program will be internationalized
only if GNU gettext has been built and installed before GNU libiconv. This
means that the first time GNU libiconv is installed, we have a circular
dependency between the GNU libiconv and GNU gettext packages, which can be
resolved by building and installing either
first libiconv, then gettext, then libiconv again,
or (on systems supporting shared libraries, excluding AIX)
first gettext, then libiconv, then gettext again.
Recall that before building a package for the second time, you need to erase
the traces of the first build by running "make distclean".
This library can be built and installed in two variants:
The library mode. This works on all systems, and uses a library
libiconv.so
and a header file
. (Both are installed
through "make install".)
To use it, simply
#include
and use the functions.
To use it in an autoconfiguring package:
If you don't use automake, append
m4/iconv.m4
to your
aclocal.m4
file.
If you do use automake, add
m4/iconv.m4
to your m4 macro repository.
Add to the link command line of libraries and executables that use
the functions the placeholder
@LIBICONV@
(or, if using libtool for
the link,
@LTLIBICONV@
). If you use automake, the right place for
these additions are the *_LDADD variables.
Note that
iconv.m4
is also part of the GNU gettext package, which
installs it in
/usr/local/share/aclocal/iconv.m4
The libc plug/override mode. This works on GNU/Linux, Solaris and OSF/1
systems only. It is a way to get good iconv support without having
glibc-2.1.
It installs a library
preloadable_libiconv.so
. This library can be used
with LD_PRELOAD, to override the iconv* functions present in the C library.
On GNU/Linux and Solaris:
$ export LD_PRELOAD=/usr/local/lib/preloadable_libiconv.so
On OSF/1:
$ export _RLD_LIST=/usr/local/lib/preloadable_libiconv.so:DEFAULT
A program's source need not be modified, the program need not even be
recompiled. Just set the LD_PRELOAD environment variable, that's it!
The
libiconv
and
libcharset
libraries
and their header files are under LGPL.
The
iconv
program
is under GPL.
Downloading libiconv
libiconv can be downloaded from
For other ways to obtain libiconv, please read
How to get GNU Software
The latest development sources can be obtained through the
savannah project
Documentation
Below are the links for the online documentation.
The
iconv
program
iconv.1.html
The library functions
iconv_open.3.html
iconv.3.html
iconv_close.3.html
iconvctl.3.html
iconv_open_into.3.html
Bug reports
Bug reports should be sent to
antispam.
gnu.org>
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Copyright (C) 1998, 2022 Free Software Foundation, Inc.
Verbatim copying and distribution of this entire article is
permitted in any medium, provided this notice is preserved.
$Date: 2026/03/07 08:57:44 $ $Author: haible $
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