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<h1>International Components for Unicode<br>
ReadMe</h1>
<p>Version: Oct 13, 2000<br>
Copyright © 1997-2000 International Business Machines Corporation
and others. All Rights Reserved.</p>
<hr>
<p><br>
<br>
</p>
<h2>Contents</h2>
<ul type="disc">
<li><a href="#news">Late Breaking News And What Is New?</a></li>
<li><a href="#introduction">Introduction</a></li>
<li><a href="#WhatContain">What the International Components for
Unicode Contain</a></li>
<li><a href="#API">API Overview</a></li>
<li><a href="#PlatformDependencies">Platform Dependencies</a></li>
<li><a href="#ImportantNotes">Important Installation Notes</a></li>
<li><a href="#HowToInstall">How to Build And Install ICU</a></li>
<li><a href="#dataHandling">How ICU Handles Data</a></li>
<li><a href="#CharsetConvert">Character Set Conversion
Information</a></li>
<li><a href="#VersionNumbers">Version Numbers In ICU</a></li>
<li><a href="#ProgrammingNotes">Programming Notes</a></li>
<li><a href="#WhereToFindMore">Where To Find More Information</a></li>
<li><a href="#SubmittingComments">Submitting Comments, Requesting
Features and Reporting Bugs</a></li>
</ul>
<h2><a name="#news">Late Breaking News And What Is New?</a></h2>
<ul>
<li><a href="#win32LibNames">Library names are changed and moved on Win32</a></li>
<li><a href="#sharedLibNote">Using Shared Data Libraries</a></li>
<li><a href="#ErrcodeChanges">Important Change Of Error Codes From
Streaming Conversion Functions</a></li>
</ul>
<hr>
<h2><a name="introduction">Introduction</a></h2>
<p>Today's software market is a global one in which it is desirable to
develop and maintain one application that supports a wide variety of
national languages. International Components for Unicode provides the
following tools to help you write language independent applications:</p>
<ul type="disc">
<li>UnicodeString supporting the Unicode 3.0 standard</li>
<li>Resource bundles for storing and accessing localized
information</li>
<li>Number formatters for converting binary numbers into text strings
for meaningful display</li>
<li>Date and time formatters for converting internal time data into
text strings for meaningful display</li>
<li>Message formatters for putting together sequences of strings,
numbers dates and other format to create messages</li>
<li>Text collation supporting language sensitive comparison of
strings</li>
<li>Text boundary analysis for finding characters, word and sentence
boundaries</li>
<li>Changing simple data files rather than modifying program code
easily localizes applications written using these tools</li>
<li>Over 150 locales supported. Visit the <a href=
"http://oss.software.ibm.com/developerworks/opensource/icu/localeexplorer">
LocaleExplorer
(http://oss.software.ibm.com/developerworks/opensource/icu/localeexplorer)</a>
site for a demonstration and a full list of supported locales or <a
href="docs/supp_loc.html">click here for a table of supported
locales</a>.</li>
</ul>
<p>It is possible to support additional locales by adding more locale
data files, with no code changes.</p>
<p>Please refer to POSIX programmer's Guide for details on what the ISO
locale ID means.</p>
<p>Your comments are important to making this release successful. We are
committed to fixing any bugs, and will also use your feedback to help
plan future releases.</p>
<p><strong><u>IMPORTANT</u>: Please make sure you understand the <a href=
"license.html">Copyright and License information</a>.</strong></p>
<p><br>
</p>
<h2><a name="WhatContain">What the International Components for Unicode
Contain</a></h2>
<p>There are two ways to download the ICU releases,</p>
<ul type="disc">
<li><strong>Official Release Snapshot:</strong><br>
If you want to use ICU (as opposed to developing it), your best bet is
to download an official, packaged ICU version of the ICU source code.
These versions are tested more thoroughly than day-to-day development
builds of the system, and they are packaged in zip and tar files for
convenient download. These packaged files can be found at <a href=
"http://oss.software.ibm.com/icu/download/index.html">http://oss.software.ibm.com/icu/download/index.html</a>.<br>
If packaged snapshot is named <strong>ICUXXXXXX.zip</strong> , XXXXXX
is the release version number.<br>
Please unzip this file. It will re-construct the source
directory.</li>
<li><strong>CVS Source Repository:</strong><br>
If you are interested in developing features, patches, or bug fixes
for ICU, you should probably be working with the latest version of the
ICU source code. You will need to check the code out of our CVS
repository to ensure that you have the most recent version of all of
the files. There are several ways to do this:</li>
<li style="list-style: none">
<ul type="circle">
<li>WebCVS:<br>
If you want to browse the code and only make occasional downloads,
you may want to use WebCVS. It provides a convenient, web-based
interface for browsing and downloading the latest version of the
ICU source code and documentation. You can also view each file's
revision history, display the differences between individual
revisions, determine which revisions were part of which official
release, and so on.</li>
<li>
WinCVS:<br>
If you will be doing serious work on ICU, you should probably
install a CVS client on your own machine so that you can do batch
operations without going through the WebCVS interface. On
Windows, we suggest the WinCVS client. The following is the
example instruction on how to download ICU via WinCVS:
<ol>
<li>Install the WinCVS client, which you can download from the
WinCVS home page.</li>
<li>In the WinCVS preferences, specify your CVSRoot to be
":pserver:anoncvs@oss.software.ibm.com:/usr/cvs/icu"<br>
with the password "anoncvs". To enter the CVSRoot value,
select "Preferences" from the "Cvs Admin" pull-down menu.
Authentication should be set to "'passwd' file on the cvs
server".</li>
<li>To "extract" the most recent version of ICU, select
"Checkout module" from the "Cvs Admin" menu. Specify "icu" for
the module name.</li>
</ol>
</li>
<li>CVS command line:<br>
You can also check out the repository anonymously on UNIX using
the following commands, after first setting your CVSROOT to point
to the ICU repository:<br>
<br>
<i>export
CVSROOT=:pserver:anoncvs@oss.software.ibm.com:/usr/cvs/icu<br>
cvs login CVS password: anoncvs<br>
cvs checkout icu<br>
cvs logout</i></li>
</ul>
</li>
</ul>
<p>For more details on how to download ICU directly from the web site,
please also see <a href=
"http://oss.software.ibm.com/icu/download/index.html">http:/oss.software.ibm.com/icu/download/index.html</a></p>
<p>Below, <strong>$Root</strong> is the placement of the icu directory in
your file system, like "drive:\...\icu" in your environment. "drive:\..."
stands for any drive and any directory on that drive that you chose to
install icu into.</p>
<table border="1" cellpadding="0" width="100%">
<caption align="left">
<strong>The following files describe the code drop</strong>
</caption>
<tr>
<td width="20%">
<p>readme.html</p>
</td>
<td width="80%">
<p>Describes the International Components for Unicode (this
file)</p>
</td>
</tr>
<tr>
<td width="20%">
<p>license.html</p>
</td>
<td width="80%">
<p>Contains IBM's public license</p>
</td>
</tr>
<tr>
<td width="20%">
<p>$Root/docs</p>
</td>
<td width="80%">
<p>API documentation for the International Components for
Unicode</p>
</td>
</tr>
</table>
<p><br>
</p>
<table border="1" cellpadding="0" width="100%">
<caption align="left">
<strong>The following directories contain source code and data
files</strong>
</caption>
<tr>
<td width="20%">
<p>$Root/source/common/</p>
</td>
<td width="80%">
<p>The utility classes, such as ResourceBundle, Unicode, Locale,
UnicodeString. The codepage conversion library API,
UnicodeConverter.</p>
</td>
</tr>
<tr>
<td width="20%">
<p>$Root/source/i18n/</p>
</td>
<td width="80%">
<p>The collation source files, Collator, RuleBasedCollator and
CollationKey.<br>
The text boundary API, which locates character, word, sentence,
and<br>
line breaks.<br>
The format API, which formats and parses data in numeric or date
format to and from text.</p>
</td>
</tr>
<tr>
<td width="20%">
<p>$Root/source/test/intltest/</p>
</td>
<td width="80%">
<p>A test suite including all C++ APIs. For information about
running the test suite, see <a href=
"docs/intltest.html">docs/intltest.html</a>.</p>
</td>
</tr>
<tr>
<td width="20%">
<p>$Root/source/test/cintltst/</p>
</td>
<td width="80%">
<p>A test suite including all C APIs. For information about running
the test suite, see <a href=
"docs/cintltst.html">docs/cintltst.html.</a></p>
</td>
</tr>
<tr>
<td width="20%">
<p>$Root/data/</p>
</td>
<td width="80%">
<p>The Unicode 3.0 data file. Please see <a href=
"http://www.unicode.org/">http://www.unicode.org/</a> for more
information.<br>
This directory also contains the resource files for all
international objects. These files are of three types:</p>
<ul type="disc">
<li>TXT files contain general locale data.</li>
<li>RES files contain non-portable locale data files which are
generated by the <strong>genrb</strong> tool.</li>
<li>UCM files which contain mapping tables {from,to} Unicode in
text format</li>
<li>CNV files are non-portable packed binary conversion data
generated by the <strong>makeconv</strong> tool.</li>
<li>icudata.dll file contains data files in a dynamic loadable
library format. At this moment, this file contains CNV files,
converter aliases, timezone data and Unicode character names.
Please read <a href="docs/udata.html">udata.html</a> for more
information.</li>
<li>icudata.dat file contains data files in a memory mapped file
format. At this moment, this file contains CNV files, converter
aliases, timezone data and Unicode character names. Please read
<a href="docs/udata.html">udata.html</a> for more
information.</li>
</ul>
</td>
</tr>
<tr>
<td width="20%">
<p>$Root/source/tools</p>
</td>
<td width="80%">
<p>Tools for generating the data files. Data files are generated by
invoking $Root/source/tools/makedata.bat on Win32 or
$Root/source/make install on Unix.</p>
</td>
</tr>
<tr>
<td width="20%">
<p>$Root/source/samples</p>
</td>
<td width="80%">
<p>Various sample programs that use ICU</p>
</td>
</tr>
</table>
<p><br>
</p>
<table border="1" cellpadding="0" width="100%">
<caption align="left">
<strong>The following directories are populated when you've built the
framework</strong><br>
(on Unix, replace $Root with the value given to the "configure"
script)
</caption>
<tr>
<td width="20%">
<p>$Root/include/</p>
</td>
<td width="80%">
<p>contains all the public header files.</p>
</td>
</tr>
<tr>
<td width="20%">
<p>$output</p>
</td>
<td width="80%">
<p>contains the libraries for static/dynamic linking or executable
programs.</p>
</td>
</tr>
</table>
<p><strong>The following shows the main directory structure of the
International Components for Unicode</strong></p>
<ul style='list-style-type: disc'>
<li>
output
<ul style='list-style-type: circle'>
<li>libraries (built)</li>
<li>programs (built)</li>
</ul>
</li>
<li>
icu-NNNN
<ul style='list-style-type: circle'>
<li>
icu
<ul style='list-style-type: square'>
<li>readme.html</li>
<li>license.html</li>
<li>include (built)</li>
<li>data</li>
<li>docs</li>
<li>
source
<ul style='list-style-type: disc'>
<li>common</li>
<li>
extra
<ul style='list-style-type: circle'>
<li>ustdio</li>
</ul>
</li>
<li>i18n</li>
<li>samples</li>
<li>
test
<ul style='list-style-type: circle'>
<li>cintltst</li>
<li>intltest</li>
</ul>
</li>
<li>
tools
<ul style='list-style-type: circle'>
<li>ctestfw</li>
<li>genrb</li>
<li>pkgdata</li>
<li>makeconv</li>
<li>...</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
<h2><a name="API">API Overview</a></h2>
<p>In the International Components for Unicode, there are two
categories:</p>
<ul type="disc">
<li>
Low-level Unicode/Resource Attributes: (<strong>icuuc</strong>
library)
<ul type="circle">
<li><a href="docs/utilCL.html">Utility Classes</a></li>
<li><a href="docs/conversion_interface.htm">Conversion
Interface</a></li>
</ul>
</li>
<li>
High-level Unicode Internationalization: (<strong>icui18n</strong>
library)
<ul type="circle">
<li><a href="docs/boundCL.html">Text Boundary Classes</a></li>
<li><a href="docs/collateCL.html">Collation Classes</a></li>
<li><a href="docs/formatCL.html">Formatting Classes</a></li>
<li>Transliterator Classes</li>
</ul>
</li>
</ul>
<p>See <a href=
"http://oss.software.ibm.com/icu/develop/codestds.html">International
Components for Unicode Coding Guidelines</a> for a discussion of code
conventions common to all library classes.</p>
<p>See also <a href="../icuhtml/aindex.html">../icuhtml/aindex.html</a>
for an alphabetical index, and <a href=
"../icuhtml/HIER.html">../icuhtml/HIER.html</a> for a hierarchical index
to detailed API documentation.<br>
<br>
</p>
<h2><a name="PlatformDependencies">Platform Dependencies</a></h2>
<p>The platform dependencies have been isolated into the following 4
files:</p>
<ul type="disc">
<li>
<u>platform.h.in:</u> Platform-dependent typedefs and defines:<br>
<br>
<ul type="circle">
<li>XP_CPLUSPLUS for C++ only.</li>
<li>TRUE and FALSE, bool_t, int8_t, int16_t etc.</li>
<li>U_EXPORT and U_IMPORT for specifying dynamic library import and
export</li>
</ul>
</li>
</ul>
<ul type="disc">
<li>
<u>putil.c:</u> platform-dependent implementations of various
functions that are platform dependent: (declared in putil.h)<br>
<br>
<ul type="circle">
<li>icu_isNaN, icu_isInfinite(double), icu_getNaN();
icu_getInfinity for handling special floating point values.</li>
<li>icu_tzset, icu_timezone, icu_tzname and time for reading
platform specific time and timezone information.</li>
<li>icu_getDefaultDataDirectory, icu_getDefaultLocaleID for reading
the locale setting and data directory.</li>
<li>icu_isBigEndian for finding the endianess of the platform.</li>
<li>icu_nextDouble is used specifically by the ChoiceFormat
API.</li>
</ul>
</li>
</ul>
<ul type="disc">
<li>
<u>mutex.h and mutex.cpp</u>: Code for doing synchronization in
multithreaded applications. If you wish to use International
Components for Unicode in a multithreaded application, you must
provide a synchronization primitive that the classes can use to
protect their global data against simultaneous modifications. See <a
href="docs/mutex.html">docs/mutex.html</a> for more information.<br>
<br>
<ul type="circle">
<li>We supply sample implementations for WinNT, Win95, Win98,
Sun/Solaris, RedHat/Linux, HP-UX and for AIX on an RS/6000.</li>
<li>If you are changing the platform-dependent files, ptypes.h and
putil.h may also be interesting, but shouldn't have to be changed.
If you think any other files than the ones mentioned above have
platform dependencies, please contact us.</li>
<li>For the Intltest test suite, intltest.cpp in
"icu/source/test/intltest/" contains the method pathnameInContext,
which must also be adapted to any new platform.</li>
</ul>
</li>
</ul>
<ul type="disc">
<li>
<u>udata.h</u>: The data-accessing interface in ICU is implemented
such that there is a lot of flexibility for reading a data file. Each
platform can tune the performance of file accessing for its
environment by choosing to implement one of the following
options:<br>
<br>
<ul type="circle">
<li>DLL</li>
<li>Memory map</li>
<li>Plain text</li>
</ul>
</li>
</ul>
<h2><a name="ImportantNotes">Important Installation Notes</a></h2>
<h3><a name="ImportantNotesWin32">Win32 Platform</a></h3>
<hr>
<h3><a name="win32LibNames">BREAKING NEWS: Library names are changed and libraries are moved on Win32</a></h3>
<p>As it was previously mentioned and proposed on <a href="http://oss.software.ibm.com/icu/archives/icu/icu.0009/msg00138.html">ICU list</a>,
ICU libraries on Win32 are now renamed and relocated. The following changes took place:</p>
<ol>
<li>in icu\lib:</li>
<ul>
<li>Debug\icuuc.lib -> icuuc17d.lib</li>
<li>Release\icuuc.lib -> icuuc17.lib</li>
<li>Debug\icui18n.lib -> icuin17d.lib</li>
<li>Release\icui18n.lib -> icuin17.lib</li>
<li>Debug\ustdio.lib -> icuio17d.lib</li>
<li>Release\ustdio.lib -> icuio17.lib</li>
</ul>
<li>in icu\bin:</li>
<ul>
<li>Debug\icuuc.dll -> icuuc17d.dll</li>
<li>Release\icuuc.dll -> icuuc17.dll</li>
<li>Debug\icui18n.dll -> icuin17d.dll</li>
<li>Release\icui18n.dll -> icuin17.dll</li>
<li>Debug\ustdio.dll -> icuio17d.dll</li>
<li>Release\ustdio.dll -> icuio17.dll</li>
</ul>
</ol>
<p>Also, ctestfw and ex toolutil (now icutu17) libraries appeared in icu\bin
and icu\lib dirs, but this shouldn't concern regular users of icu.</p>
<h4>What to do, how to cope?</h4>
<p>When you first try to compile your programs with new version of icu,
compilation will fail. The following steps are required:</p>
<ol>
<li>change your path from ...\icu\bin\debug or ...\icu\bin\release to just ...\icu\bin</li>
<li>make the same change for MSVC executable directory setting (tools->options->directories)</li>
<li>In all your .dsp files (project settings), on linker tab change input libraries according to the above scheme. You want to do it for both debug and release versions.</li>
</ol>
<p>When a new, binary incompatible version appears after 1.7, the libraries will change the version number, so you will have to rename libraries in your projects again. However, this way you can have several versions of icu on the same machine and change the libraries for different programs without having to change path settings on your machine.</p>
<hr>
<p>If you are building on the Win32 platform, it is important that you
understand a few build details:</p>
<p><u>DLL directories and the PATH setting:</u> As delivered, the
International Components for Unicode build as several DLLs. These DLLs
are placed in the directories "icu\bin\Debug" and "icu\bin\Release". You
must add either of these directories to the PATH environment variable in
your system, or any executables you build will not be able to access
International Components for Unicode libraries. Alternatively, you can
copy the DLL files into a directory already in your PATH, but we do not
recommend this. You can wind up with multiple copies of the DLL and wind
up using the wrong one.</p>
<p><u>To change your PATH:</u> When you are not using the debug version,
you will want to change the "Debug" part of the path to "Release" instead
(the $Root is the root ICU installation directory e.g.
drive:\installation-directory\icu).</p>
<ul type="disk">
<li><strong>Windows 2000</strong>: Use the System Icon in the Control
Panel. Pick the "Advanced" tab. Select the "Environment Variables..."
button. Select the variable PATH in the lower box, and select the lower
"Edit..." button. In the "Variable Value" box, append the string
";$Root\bin\Debug" to the end of the path string. If there is nothing
there, just type in "$Root\bin\Debug". Click the Set button, then the
OK button.</li>
<li><strong>Windows NT</strong>: Use the System Icon in the Control
Panel. Pick the "Environment" tab, and select the variable PATH in the
lower box. In the "value" box, append the string ";$Root\bin\Debug" at
the end of the path string. If there is nothing there, just type in
"drive:\...\icu\bin\Debug". Click the Set button, then the Ok
button.</li>
<li><strong>Windows 95/98/ME</strong>: Edit the autoexec.bat, and add
the following line to the end of file, "SET
PATH=%PATH%;$Root\bin\Debug"</li>
</ul>
<p><u>Link with Runtime libraries:</u> All the DLLs link with the C
runtime library "Debug Multithreaded DLL" or "Multithreaded DLL." (This
is changed through the Project Settings dialog, on the C/C++ tab, under
Code Generation.) It is important that any executable or other DLL you
build which uses the International Components for Unicode DLLs links with
these runtime libraries as well. If you do not do this, you will
seemingly get memory errors when you run the executable.<br>
</p>
<h3><a name="ImportantNotesOS390">OS/390 Platform</a></h3>
<p>If you are building on the OS/390 UNIX System Services platform, it is
important that you understand a few details:</p>
<ul>
<li>The gnu utilities gmake and gzip/gunzip are needed and can be
obtained for OS/390 from <a href=
"http://www.mks.com/">http://www.mks.com/</a>. Search for OS/390,
register, and follow download directions.</li>
<li>
Encoding considerations: The source code assumes that it is compiled
with codepage 1047 (to be exact, the UNIX System Services variant of
it). The pax command converts all of the source code files from ASCII
to codepage 1047 (USS) EBCDIC. However, some files are binary files
and must not be converted, or must be converted back to their
original state. Those files are:
<ul>
<li>All the .brk files located in the icu/data directory
(icu/data/*.brk)</li>
<li>icu/source/test/testdata/uni-text.txt</li>
<li>icu/source/test/testdata/th18057.txt</li>
</ul>
Such a conversion can be done using iconv:<br>
<code>iconv -f IBM-1047 -t ISO8859-1 uni-text.txt >
uni-text.txt</code>
</li>
<li>
DLL directories and the LIBPATH setting: Building and testing ICU
needs the ICU libraries on the LIBPATH. In other words, the LIBPATH
should contain (each path prepended with the root directory that
contains the icu directory):
<ul>
<li>icu/source/common</li>
<li>icu/source/i18n</li>
<li>icu/source/tools/ctestfw</li>
<li>icu/source/tools/toolutil</li>
<li>icu/source/extra/ustdio</li>
</ul>
</li>
<li>
<p>OS/390 supports both native S/390 hexadecimal floating point and,
with Version 2.6 and later, IEEE binary floating point. This is a
compile time option. Applications built with IEEE should use ICU dlls
that are built with IEEE (and vice versa). The environment variable
IEEE390=1 will cause the OS/390 version of ICU to be built with IEEE
floating point. The default is native hexadecimal floating point.<br>
<em>Important:</em> Currently (ICU 1.4.2), native floating point
support is sufficient for codepage conversion, resource bundle and
UnicodeString operations, but the Format APIs, especially
ChoiceFormat, require IEEE binary floating point.</p>
<p>Examples for configuring ICU:<br>
Debug build: <code>IEEE390=1 ./configure</code><br>
Release build: <code>CFLAGS=-2 IEEE390=1 ./configure</code></p>
</li>
<li>Since the default make on OS/390 is not gmake, pkgdata tool
requires that the environment variable MAKE be set to path to
gmake.</li>
<li>The makedep executable that is used with the OS/390 ICU build
process is not shipped with ICU. It is available at the <a href=
"http://www.s390.ibm.com/products/oe/bpxa1ty2.html">OS/390 UNIX - Tools
and Toys</a> site. The PATH environment variable should be updated to
contain the location of this executable prior to build. Alternatively,
makedep may be moved into an existing PATH directory.</li>
<li>When running the test suite, the TZ environment variable should be
set to export TZ="PST8PDT" so that time zone comparisons are
correct.</li>
</ul>
<h3><a name="ImportantNotesOS400">OS/400 Platform</a></h3>
<p>ICU Reference Release 1.4.0 contains partial support for the 400
platform, but additional work by the user is currently needed to get it
to build completely. A future release of the ICU should work
out-of-the-box under OS/400.</p>
<ul>
<li>
Requirements:
<ul>
<li>QSHELL interpreter installed (install base option 30, operating
system)</li>
<li>QShell Utilities, PRPQ 5799-XEH</li>
<li>ILE C++ for AS/400, PRPQ 5799-GDW</li>
<li>GNU facilities (the gnu facilities are currently available by
request only. Send e-mail to <a href=
"mailto:rchasgo400@us.ibm.com">rchasgo400@us.ibm.com</a> )</li>
</ul>
<!-- end requirements -->
</li>
<li>
Build environment setup:
<ol>
<li>Create AS400 target library. This library will be the target
for the resulting modules, programs and service programs. You will
specify this library on the OUTPUTDIR environment variable in step
2.</li>
<li>
Set up the following environment variables in your build process
(use ADDENVVAR or WRKENVVAR CL commands)
<div style="margin-left: 2em">
CC - '/usr/bin/icc'<br>
CXX - ' /usr/bin/icc'<br>
MAKE - '/usr/bin/gmake'<br>
OUTPUTDIR - <i>identifies target as400 library for *module,
*pgm and *srvpgm objects</i>
</div>
</li>
<li>Add QCXXN, to your build process library list. This results in
the resolution of CRTCPPMOD used by the icc compiler</li>
<li>
Configure the Makefiles (see configure below)
<strong>Note:</strong> Verify that the mh-os400 configure file is
used.
<ul>
<li>Run 'configure --host=as400-os400'</li>
<li>The 'clean' and 'install' targets will not work without
changes because of symbolic links. To delete the target module,
program, or service programs replace <tt>rm -rf</tt> with
<strong>$(RMV)</strong>, and in the library installation
targets (install-library) change <tt>$(INSTALL)</tt> to
<strong><tt>$(INSTALL-S)</tt></strong>.</li>
</ul>
</li>
<li>gmake -e (-e to pickup the compilers)</li>
</ol>
<!-- end build environment -->
</li>
</ul>
<strong>Note:</strong> About the NULL pointer checks
<div style="margin-left: 2em">
In common/ucnv.c and common/unistr.c (search for U_MAX_PTR), there are
additional checks for NULL pointers. This is because pointer comparison
works differently on the AS/400 architecture.
</div>
<h2><a name="HowToInstall">How To Build And Install ICU</a></h2>
<h3><a name="HowToInstallWindows">How To Build And Install On
Windows</a></h3>
<p>Building International Components for Unicode requires:</p>
<ul type="disc">
<li>Microsoft NT 3.51 or above</li>
<li>Microsoft Visual C++ 6.0 (Service Pack 2 is required to work with
the release build of max speed optimization).</li>
</ul>
<p>The steps are:</p>
<ol start="1" type="1">
<li>Unzip the icu-XXXX.zip file, type "unzip -a icu-XXXX.zip -d
drive:\directory" under command prompt or use WinZip.
drive:\directory\icu is the root ($Root) directory (you may but don't
need to place "icu" into another directory). If you change the root,
you will change the project settings accordingly in EACH makefile in
the project, updating the "include" and "library" paths.</li>
<li>Set the environment variable <strong>ICU_DATA</strong> to the full
pathname of the data directory. The trailing "\" is required after the
directory name (e.g. "$Root\data\" will work, but the value
"$Root\data" is not acceptable). This environment variable indicates
where the locale data files and conversion mapping tables are
located.</li>
<li>Be sure that the ICU binary directory, $Root\bin\[Release|Debug],
is included in the <strong>PATH</strong> environment variable. The
tests may not work without the DLL files in the path.</li>
<li>Set the <strong>TZ</strong> environment variable to
<strong>PST8PDT</strong>. The tests will not work in any other
timezone.</li>
<li>Use Microsoft Visual C++ 6.0 to open the
"$Root\source\allinone\allinone.dsw" workspace (This workspace includes
all the International Components for Unicode libraries, necessary ICU
building tools, and the intltest and cintltest test suite
projects).</li>
<li>Set the active Project to the "all" project. To do this: Choose
"Project" menu, and select "Set active project". In the submenu, select
the "all" workspace.</li>
<li>Set the active configuration to "Win32 Debug" or "Win32 Release"
(See note below).</li>
<li>Choose the "Build" menu and select "Rebuild All". If you want to
build the Debug and Release configurations at the same time, choose
"Build" menu and select "Batch Build..." instead (and mark all
configurations as checked), then click the button named "Rebuild All".
The "all" workspace will build all the test programs as well as the
tools for generating binary locale data files. The "makedata" project
will be run automatically to convert the locale data files from text
format into icudata.dll.</li>
<li>Run the C++ test suite, "intltest". To do this: set the active
project to "intltest", and press F5 to run it.</li>
<li>Run the C test suite, "cintltst". To do this: set the active
project to "cintltst", and press F5 to run it.</li>
<li>Make sure that both "cintltst" and "intltest" passed without any
errors. The return codes are non-zero when they do not pass. Visual C++
will display the return codes in the debug tag of the output window.
When "intltest" and "cintltest" return 0, it means that everything is
installed correctly.</li>
<li>Reset the <strong>TZ</strong> environment variable to its original
value, unless you plan on testing ICU any further.</li>
<li>You are now able to develop applications with ICU.</li>
</ol>
<p><strong>Note:</strong> To set the active configuration, two different
possibilities are:</p>
<ul type="disc">
<li>Choose "Build" menu, select "Set Active Configuration", and select
"Win32 Release" or "Win32 Debug".</li>
<li>Another way is to select "Customize" in the "Tools" menu, select
the "Toolbars" tab, enable "Build" instead of "Build Minibar", and
click on "Close". This will bring up a toolbar which you can move aside
the other permanent toolbars at the top of the MSVC window. The
advantage is that you now have an easy-to-reach pop-up menu that will
always show the currently selected active configuration. Or, you can
drag the project and configuration selections and drop them on the menu
bar for later selection.</li>
</ul>
<p>It is also possible to build each library individually, using the
workspaces in each respective directory. They have to be built in the
following order:<br>
</p>
<ol start="1" type="1">
<li>common</li>
<li>i18n</li>
<li>makedata (which invokes makeconv, genrb, genccode, etc.)</li>
<li>ctestfw</li>
<li>intltest and cintltst, if you want to run the test suite.</li>
</ol>
Regarding the test suite, please read the directions in <a href=
"docs/intltest.html">docs/intltest.html</a> and <a href=
"docs/cintltst.html">docs/cintltst.html</a><br>
<br>
<h3><a name="HowToInstallUnix">How To Build And Install On Unix</a></h3>
<p>There is a set of Makefiles for Unix that supports Linux w/gcc,
Solaris w/gcc and Workshop CC, AIX w/xlc and OS/390 with C++.</p>
<p>Building International Components for Unicode on Unix requires:</p>
<p>A UNIX C++ compiler, (gcc, cc, xlc_r, etc...) installed on the target
machine. A recent version of GNU make (3.7+). OS/390 gnu utilities for
both make (gmake) and zip (gzip/gunzip) can be found at the MKS web site
at <a href="http://www.mks.com">http://www.mks.com</a>. Please do a
search on "os/390".</p>
<p>The steps are:</p>
<ol start="1" type="1">
<li>Decompress the icuXXXX.tar (or icuXXXX.tgz) file.</li>
<li>Before running the test programs or samples, please set the
environment variable <strong>ICU_DATA</strong>, the full pathname of
the data directory, to indicate where the locale data files and
conversion mapping tables are. If this variable is not set, the default
user data directory will be used. The trailing "/" is required after
the directory name (e.g. "$Root/data/" will work, but the value
"$Root/data" is not acceptable). The <strong>TZ</strong> environment
variable does not need to be set.</li>
<li>Change directory to the "icu/source".</li>
<li>If it is not already set, please set the executable flag for the
following files (by executing 'chmod +x' command): runConfigureICU,
configure, install.sh and config.*,</li>
<li>You also need to set other environment variables for different
build systems. Use this <a href="docs/build_env.htm">table</a> or the
provided <a href="source/runConfigureICU">script</a>.</li>
<li>Type "./configure" or type "./configure --help" to print the
available options.</li>
<li>Type "make" to compile the libraries and all the data files. On
OS/390, both IEEE binary floating point and native S/390 hexadecimal
floating point calculations are supported. The default is to build with
native floating-point support. Please set the environment variable
IEEE390=1 if you would like to make the ICU DLLs with IEEE floating
point support.</li>
<li>Optionally, type "make check" to verify the test suite.</li>
<li>Type "make install" to install.</li>
</ol>
<p>Regarding the test suite, please read the directions in <a href=
"docs/intltest.html">docs/intltest.html</a> and <a href=
"docs/cintltst.html">docs/cintltst.html</a>.</p>
<p>Some platforms use package management tools to control the
installation and uninstallation of files on the system, as well as
the integrity of the system configuration. You may want to check if
ICU can be packaged for your package management tools by looking
into the "packaging" directory. (Please note that if you are using
a snapshot of ICU from CVS, it is probable that the packaging scripts
or related files are not up to date with the contents of ICU at this
time, so use them with caution.)</p>
<p>It is also possible to build each library individually, using the
Makefiles in each respective directory. They have to be built in the
following order:</p>
<ol start="1" type="1">
<li>common</li>
<li>i18n</li>
<li>makeconv</li>
<li>genrb</li>
<li>gentz</li>
<li>genccode</li>
<li>ctestfw</li>
<li>intltest and cintltst, if you want to run the test suite.</li>
</ol>
<h3><a name="sharedLibNote">Using Shared Data Libraries</a></h3>
<p style='margin-left:.5in'>HP/UX has a documented characteristic where
the shl_unload() function always unloads a library, regardless of how
many times the library has been loaded. Most operating systems
reference-count libraries as they are opened. In the future (Jitterbug
414) this may be corrected in the ICU, but at present we work around this
problem by simply NOT ever unloading shared libraries. This means that
once a data library is loaded (ex: libicudata.sl) by a process, it cannot
be unloaded and replaced without stopping and restarting the process.</p>
<h2><a name="dataHandling">How ICU handles data</a></h2>
<h3><a name="addDataHandling">How to add a locale data file</a></h3>
<p>To add locale data files to International Components for Unicode do
the following:</p>
<ol start="1" type="1">
<li style='margin-top:.25in'>Create a file containing the key-value
pairs which value you are overriding from the parent locale data file.
Make sure the filename is the locale ID with the extension ".txt". We
recommend you copy a parent file and change the values that need to be
changed, remove all other key-pairs. Be sure to update the locale ID
key (the outmost brace) with the name of the locale id your a
creating.</li>
<li style='margin-top:.25in'>Name the file with locale ID you are
creating with a ".txt" at the end (e.g. the file "fr_BF.txt" would
create a locale that inherits all the key-value pairs from
"fr.txt".).</li>
<li style='margin-top:.25in'>Add the name of that file (without the
".txt" extension) as a single line in "index.txt" file in the default
locale directory (icu/data/).</li>
<li style='margin-top:.25in'>Regenerate the data DLL file. Please see
"<a href="#HowToInstall">How to Install</a>" section for more details
on how to verify the ICU release.</li>
</ol>
<h3><a name="addRBDataToApp">How to add resource bundle data to your
application</a></h3>
<p>Adding resource bundle data to your application is simple. Just create
the resource bundle files with the right format and names in your
application directory tree. For more information on the resource bundle
file format see the <a href=
"../icuhtml/ResourceBundle.html#DOC.DOCU">resource bundle
documentation</a> or the <a href=
"http://oss.software.ibm.com/icu/userguide/Fallbackmechanism.html">User's
Guide</a>).</p>
<p><strong>Note:</strong> resource bundle tag names should contain only
invariant 7-bit ASCII characters (e.g. ones from the following set:
<code>A-Z, a-z, 0-9, <SP>, ", %, &, `, (, ), *, +, ,, -, ., /,
:, ;, <, =, >, ?, _)</code>. Use that same directory name (absolute
path) when instantiating a resource bundle at run time.</p>
<h3><a name="WhereCollation">Where Collation Data is stored</a></h3>
<p>Collation data is stored as a binary object inside of the corresponding
resource. The source for the tailorings
is stored in a corresponding ASCII text file (resource bundle source)
indicated by a "CollationElements" tag . For instance, the data for
de_CH is stored with
a tag "CollationElements" in a file named "de_CH.txt".
(The data is stored in a tag named '%%CollationElements').
Reading the
collation data from these files can be time-consuming, especially for
large pieces of data that occur in languages such as Japanese. For this
reason, the Collation Framework implements a second file format, a
performance-optimized, non-portable, binary format. These binary formats
are generated automatically by the framework when genrb is run on the
specific locales.
<h2><a name="CharsetConvert">Character Set Conversion
Information</a></h2>
<p>The charset conversion library provides ways to convert simple text
strings (e.g., char*) such as ISO 8859-1 to and from Unicode. The
objective is to provide clean, simple, reliable, portable and adaptable
data structures and algorithms to support the International Components
for Unicode's character codeset Conversion APIs. The conversion data in
the library originated from the NLTC lab in IBM. The IBM character set
conversion tables are publicly available in the published IBM document
called "CHARACTER DATA REPRESENTATION ARCHITECTURE - REFERENCE AND
REGISTRY". The character set conversion library includes single-byte,
double-byte and some UCS encodings to and from Unicode. This document can
be ordered through Mechanicsberg and it comes with 2 CD ROMs which have
machine-readable conversion tables on them. The license agreement is
included in International Components for Unicode agreement.</p>
<p>Click <a href="data/convrtrs.txt">here</a> to view converters
implemented in ICU. To see converters in action, please visit <a href=
"http://oss.software.ibm.com/developerworks/opensource/icu/localeexplorer/?converter&">
http://oss.software.ibm.com/developerworks/opensource/icu/localeexplorer/?converter&</a></p>
<p>To order the document in the US you can call 1-800-879-2755 and
request document number SC09-2190-00. The cost of this publication is
$75.00 US not including tax.</p>
<h2><a name="VersionNumbers">Version Numbers In ICU</a></h2>
<p>ICU supports extensive versioning of its code and data. Versioning
allows clients to determine when parts of ICU change, and what the effect
of the change is.</p>
<p>ICU as a whole has a version number. ICU components such as Collator
have their own distinct version numbers. Each resource bundle, including
all the locale data resource bundles, has its own version number.
Individual tagged items within a resource bundle have their own version
numbers.</p>
<p>All version numbers are in the form of a UVersionInfo structure, which
is an array of four unsigned bytes. These bytes are:</p>
<ul>
<li>0: Major version number</li>
<li>1: Minor version number</li>
<li>2: Milli version number</li>
<li>3: Patch version number</li>
</ul>
<p>UVersionNumber structures can be converted to and from string
representations as dotted integers, such as "1.4.5.0", using the
u_versionToString() and u_stringToVersion() functions.</p>
<p>Version numbers monotonically increase as changes are made. Two
UVersionInfo structure may be compared using binary comparison (memcmp)
to see which is larger (newer). It only makes sense to compare the same
flavor of version number; you cannot compare the ICU version number to
the Collator version number, for instance.</p>
<p>The interpretation of version numbers depends on what is being
described.</p>
<h3><a name="VersionNumbersRelease">ICU Release Version Number</a></h3>
<p>0 (Major): Reference release with major feature addition or
change.</p>
<p>1 (Minor): Reference release without major feature addition.</p>
<p>2 (Milli): Maintenance update to the reference releases.</p>
<p>3 (Patch): Enhancement/patch update.</p>
<h3><a name="VersionNumbersCode">Code Component Version Numbers</a></h3>
<p>0 (Major): Breaking change. Results and data generated by the new
version are incompatible with those generated by the preceding version.
<em>Example</em>: In ICU 1.5, the implementation of ResourceBundle
changed drastically. The data structure, algorithm for parsing data, and
so on are completely different in 1.5. This required an increment of the
major version number.</p>
<p>1 (Minor): Backward-compatible change. The new version of the code can
read or use data generated by the old version, but the old version cannot
read or use data generated by the new version. <em>Example</em>: The
delimiter in the CollationKey gets changed from 0x0000 to 0xFFFF. The
algorithm keeps track of the differences and recognize these two
different formats before and after a particular release.</p>
<p>2 (Milli): Compatible change. Results and data generated by the new
version are compatible with those generated by the preceding version.
<em>Example</em>: A byte in the reserved bytes in the data structure is
now used as a flag/bitmask or whatever, e.g. UDataInfo. The size of the
data structure is changed and new code is added to check for this flag.
No other changes are made.</p>
<p>3 (Patch): Enhancement. A minor change. <em>Example</em>: Performance
enhancements applied to the code but no changes other than that.</p>
<h3><a name="VersionNumbersData">Data Component Version Numbers</a></h3>
<p>0 (Major): Incompatible format change. The layout or format of the
data has changed. For example, an additional array element has been
added, or an additional tag. <em>Example</em>: ICU 1.6 changes the
element layout in "CollationElements". We changed this from a tag with
plain string value to a tagged array with 3 new subtags, "Version",
"Override" and "Sequence". This change is incompatible with pre-1.6 code
and data.</p>
<p>1 (Minor): Backward-compatible format change. A change that can be
read and used by previous versions of ICU, but that adds data used by
newer versions. <em>Example</em>: We added a new tag called "Author" to
the data file. The only difference between the previous version of the
data files and the current version is this tag.</p>
<p>2 (Milli): Compatible change. A change to the data without
modification of the format. <em>Example</em>: We updated the value of a
tag "LocaleID" from "041C" to "3801". No other changes were made.</p>
<p>3 (Patch): Enhancement. A minor change. <em>Example</em>: We changed
the comments in the data file, perhaps the copyright notices.</p>
<h3><a name="VersionNumbersRB">Resource Bundles and Elements</a></h3>
<p>The data stored in resource bundles is tagged with version numbers. A
resource bundle can contain a tagged string named "Version" that declares
the version number in dotted-integer format. <em>Example</em>:</p>
<pre>
en {
Version { "1.0.3.5" }
...
}
</pre>
<p>A resource bundle may omit the "Version" element, in which case it
will inherit one along the usual chain. <em>Example</em>: If the resource
bundle en_US contained no "Version" element, it would inherit "1.0.3.5"
from en.</p>
<p>If inheritance passes all the way to the root resource bundle and it
contains no "Version" resource, then the default version number 1.0.0.0
is returned.</p>
<p>Elements within a resource bundle may also contain version numbers,
for example:</p>
<pre>
be {
CollationElements {
Version { "1.0.0.0" }
...
}
}
</pre>
<p>Here the CollationElements data is version 1.0.0.0. This version may
differ from the version of the enclosing bundle.</p>
<p>If a resource element lacks a "Version" element, then it inherits the
"Version" element of its enclosing resource bundle. (This is a special
case; in general, resource bundle elements do not inherit data from
enclosing structures.) <em>Example</em>:</p>
<pre>
en {
Version { "1.0.3.5" }
...
}
en_US {
CollationElements {
...(contains no "Version" element)
}
}
</pre>
<p>Here, the version of the CollationElements in en_US is 1.0.3.5. It
inherits the en_US version, which is inherited from en.</p>
<p><strong>Note:</strong> The API and code to fully support the mechanism
described above is not in place yet as of ICU 1.6. See <a href=
"#VersionNumbersFuture">Future Enhancements</a> below.</p>
<h3><a name="VersionNumbersWhatComponents">What Components are
Versioned</a></h3>
<p>Currently, the following components are versioned.</p>
<ul>
<li>The version of ICU as a whole is returned by
<code>u_getVersion()</code>.</li>
<li>The version of a ResourceBundle is returned by
<code>ures_getVersion()</code> and
<code>ResourceBundle::getVersion()</code>. This is a data version
number for the bundle as a whole.</li>
<li>The version of the Unicode character data underlying ICU is
returned by <code>u_getUnicodeVersion()</code> and
<code>Unicode::getUnicodeVersion()</code>. This version reflects the
numbering of the Unicode releases; see <a href=
"http://www.unicode.org">http://www.unicode.org</a>.</li>
<li>The version of the Collator is returned by
<code>Collator::getVersion()</code>. This is a code version number for
the collation code and algorithm.</li>
</ul>
<h3><a name="VersionNumbersFuture">Future Enhancements</a></h3>
<ul>
<li>The ResourceBundle version number inheritance mechanism is not
fully implemented and tested.</li>
<li>The resource element version number is not implemented at all. API
for this does not yet exist.</li>
<li>Versioning of a RuleBasedCollator's data is only possible through
the ResourceBundle API. There should probably be API on
RuleBasedCollator (or Collator) to obtain the data version number.</li>
<li>Versioning of the Normalizer data is not implemented.</li>
<li>Versioning of the Normalizer algorithm is not implemented.</li>
<li>Versioning of the Transliterators is not implemented.</li>
<li>Versioning of formatters, break iterators, and so on is not
implemented.</li>
</ul>
<h2><a name="ProgrammingNotes">Programming Notes</a></h2>
<h3><a name="ReportingErrors">Reporting Errors</a></h3>
<p>In order for the code to be portable, only a subset of the C++
language that will compile correctly on even the oldest of C++ compilers
(and also to provide a usable C interface) can be used in the
implementation, which means that there's no use the C++ exception
mechanism in the code.</p>
<p>After considering many alternatives, the decision was that every
function that can fail takes an error-code parameter by reference. This
is always the last parameter in the function’s parameter list. The
ErrorCode type is defined as a enumerated type. Zero represents no error,
positive values represent errors, and negative values represent non-error
status codes. Macros were provided, SUCCESS and FAILURE, to check the
error code.</p>
<p>The ErrorCode parameter is an input-output parameter. Every function
tests the error code before doing anything else, and immediately exits if
it’s a FAILURE error code. If the function fails later on, it sets
the error code appropriately and exits without doing any other work
(except, of course, any cleanup it has to do). If the function encounters
a non-error condition it wants to signal (such as "encountered an
unmapped character" in transcoding), it sets the error code appropriately
and continues. Otherwise, the function leaves the error code
unchanged.</p>
<p>Generally, only functions that don’t take an ErrorCode
parameter, but call functions that do, have to declare one. Almost all
functions that take an ErrorCode parameter and also call other functions
that do merely have to propagate the error code they were passed down to
the functions they call. Functions that declare a new ErrorCode parameter
must initialize it to ZERO_ERROR before calling any other functions.</p>
<p>The rationale here is to allow a function to call several functions
(that take error codes) in a row without having to check the error code
after each one. [A function usually will have to check the error code
before doing any other processing, however, since it is supposed to stop
immediately after receiving an error code.] Propagating the error-code
parameter down the call chain saves the programmer from having to declare
one everywhere, and also allows us to more closely mimic the C++
exception protocol.</p>
<h3><a name="FuncDataNaming">C Function and Data Type Naming</a></h3>
<p><strong>Function names.</strong> If a function is identical (or almost
identical) to an ANSI or POSIX function, we give it the same name and (as
much as possible) the same parameter list. A "u" is prepended onto the
beginning of the name.</p>
<p>For functions that exist prior to version 1.2.1, that the function
name should begin with a lower-case "u". After the "u" is a short code
identifying the subsystem it belongs to (e.g., "loc", "rb", "cnv",
"coll", etc.). This code is separated from the actual function name by an
underscore, and the actual function name can be anything. For
example,</p>
<pre>
UChar* uloc_getLanguage(...);
void uloc_setDefaultLocale(...);
UChar* ures_getString(...);
</pre>
<p><strong>Struct and enum type names.</strong> For structs and enum
types, the rule is that their names begin with a capital "U." There is no
underscore for struct names.</p>
<pre>
UResourceBundle;
UCollator;
UCollationResult;
</pre>
<p><strong>Enum value names.</strong> Enumeration values have names that
begin with "UXXX" where XXX stands for the name of the functional
category.</p>
<pre>
UNUM_DECIMAL;
UCOL_GREATER;
</pre>
<p><strong>Macro names.</strong> Macro names are in all caps, but there
are currently no other requirements.</p>
<p><strong>Constant names.</strong> Many constant names (constants
defined with "const", not macros defined with "#define" that are used as
constants) begin with a lowercase k, but this isn’t universally
enforced.</p>
<h3><a name="OverflowHandling">Preflighting and Overflow
Handling</a></h3>
<p>In ICU's C APIs, the user needs to adhere to the following principles
for consistency across all functional categories:</p>
<ol start="1" type="1">
<li>All the Unicode string processing should be expressed in terms of a
UChar* buffer that is always null terminated.</li>
<li>The APIs assume that the input string parameters are statically
allocated fix-sized character buffers.</li>
<li>When the value a function is going to return is already stored as a
constant value in static space (e.g., it’s coming from a fixed
table, or is stored in a cache), the function will just return the
const UChar* pointer.</li>
<li>When the function can’t return a UChar* to storage the user
doesn’t have to delete, the caller needs to pass in a pointer to
a character buffer that the function can fill with the result. This
pointer needs to be accompanied by a <code>int32_t</code> parameter
that gives the size of the buffer.</li>
</ol>
<p>To find out how large the result buffer should be, ICU provides a
<strong>preflighting</strong> C interface. The interface works like
this:</p>
<ol start="1" type="1">
<li>When using the "<strong>preflighting</strong>" option: you need to
pass the function a <code>NULL</code> pointer for the buffer pointer,
and the function returns the actual size of the result. You can then
choose to allocate a buffer of the correct size and re-run the
operation if you would like to.</li>
<li>After allocating a buffer of some reasonable size on the stack and
passes that to the function, if the result can fit in that buffer,
everything works fine. If the result doesn’t fit, the function
will return the actual size needed. You can then allocate a buffer of
the correct size on the heap and try calling the same function
again.</li>
<li>Now you have created a buffer of some reasonable size on the stack
and passes it to the function. If you don't care about the completeness
of the result and the allocated buffer is too small, you can continue
on using the truncated result.</li>
</ol>
<p>The following three options demonstrates how to use the preflighting
interface,</p>
<hr>
<pre>
/**
* @param result is a pointer to where the actual result will be.
* @param maxResultSize is the number of characters the
* buffer pointed to be result has room for.
* @return The actual length of the result including the
* terminating <code>NULL</code>.
*/
int32_t doSomething( /* input parameters */,
UChar* result,
int32_t maxResultSize,
UErrorCode* err);
</pre>
<hr>
<p>In this sample, if the actual result doesn’t fit in the space
available in <code>maxResultSize</code>, this function returns the amount
of space necessary to hold the result, and result holds as many
characters of the actual result as possible. If you don’t care
about this, no further action is necessary. If you <i>do</i> care about
the truncated characters, you can then allocate a buffer on the heap of
the size specified by the return value and call the function again,
passing <i>that</i> buffer’s address for result.</p>
<p>All preflighting functions have a fill-in <code>ErrorCode</code>
parameter (and follow the normal <code>ErrorCode</code> rules), even if
they are not currently doing so. Buffer overflow would be treated as a
FAILURE error condition, but would <i>not</i> be reported when the caller
passes in <code>NULL</code> for <code>actualResultSize</code>
(presumably, a <code>NULL</code> for this parameter means the client
doesn’t care if he got a buffer overflow). All other failing error
conditions will overwrite the "buffer overflow" error, e.g.
<code>MISSING_RESOURCE_ERROR</code> etc..</p>
<h3><a name="ArrayReturn">Arrays as return types</a></h3>
<p>Returning an array of strings is fairly easy in C++, but very hard in
C. Instead of returning the array pointer directly, we opted for an
iterative interface instead: split the function into two functions. One
returns the number of elements in the array, and the other one returns a
single specified element from the array.</p>
<hr>
<pre>
int32_t countArrayItems(/* parameters */);
int32_t getArrayElement(int32_t elementIndex,
/* other parameters */,
UChar* result,
int32_t maxResultSize,
UErrorCode* err);
</pre>
<hr>
<p>In this case, iterating across all the elements in the array would
amount to a call to the count() function followed by multiple calls to
the getElement() function.</p>
<hr>
<pre>
UChar element[50];
for (i = 0; i < countArrayItems(...); i++) {
getArrayItem(i, ..., element, 50, &err);
/* do something with element */
}
</pre>
<hr>
<p>In the case of the resource bundle <code>ures_XXXX</code> functions
returning 2-dimensional arrays, the getElement() function takes both x
and y coordinates for the desired element, and the count() function
returns the number of arrays (x axis). Since the size of each array
element in the resource 2-D arrays should always be the same, this
provides an easy-to-use C interface.</p>
<hr>
<pre>
void countArrayItems(int32_t* rows,
int32_t* columns,
/* other parameters */);
int32_t get2dArrayElement(int32_t rowIndex,
int32_t colIndex,
/* other parameters */,
UChar* result,
int32_t maxResultSize,
UErrorCode* err);
</pre>
<hr>
<h3><a name="ErrcodeChanges">Important Change Of Error Codes From
Streaming Conversion Functions</a></h3>
<p>We have decided to make a semantic change to the conversion API which
affects applications using ICU that are migrated to use ICU version 1.6
compared to earlier ICU versions:<br>
The error code that is set from streaming conversion like</p>
<pre>
ucnv_fromUnicode() - ucnv_toUnicode()
ucnv_fromUChars() - ucnv_toUChars()
scsu_compress() - scsu_decompress()
</pre>
when the target buffer is full but the source not empty is changed from
<code>U_INDEX_OUTOFBOUNDS_ERROR</code> to
<code>U_BUFFER_OVERFLOW_ERROR</code>. This change makes the error codes
more consistent with their names and with their use in other icu
APIs.<br>
<br>
<p>You need to test for this new error code if your code uses ICU for
conversion and used the old error code. ucnv.h and scsu.h are updated
with this information. Please search in your source code for
<code>U_INDEX_OUTOFBOUNDS_ERROR</code>. If it is used with the above
functions (<em>not</em> with <code>ucnv_getNextUChar()</code>), then you
need to change it to <code>U_BUFFER_OVERFLOW_ERROR</code> in order to get
your code to work with icu 1.6.</p>
<p>See the updated sample code in <code>icu/source/samples</code>. All
samples are updated. See <a href=
"http://oss.software.ibm.com/developerworks/opensource/icu/bugs?findid=516">
jitterbug 516</a> for details. This was discussed in july 2000 on the icu
mailing list. Please see the list archive for the <a href=
"http://oss.software.ibm.com/icu/archives/icu/icu.0007/msg00142.html">discussion</a>.</p>
<h2><a name="WhereToFindMore">Where To Find More Information</a></h2>
<p><a href=
"http://oss.software.ibm.com/icu/">http://oss.software.ibm.com/icu/</a>
is a pointer to general information about the International Components
for Unicode.</p>
<p><a href="docs/udata.html">docs/udata.html</a> is a raw draft of ICU
data handling.</p>
<p><a href="../icuhtml/aindex.html">icuhtml/aindex.html</a> is an
alphabetical index to detailed API documentation.<br>
<a href="../icuhtml/HIER.html">icuhtml/HIER.html</a> is a hierarchical
index to detailed API documentation.</p>
<p><a href="docs/collate.html">docs/collate.html</a> is an overview to
Collation.</p>
<p><a href="docs/BreakIterator.html">docs/BreakIterator.html</a> is a
diagram showing how BreakIterator processes text elements.</p>
<p><a href=
"http://www.ibm.com/developer/unicode/">http://www.ibm.com/developer/unicode/</a>
is a pointer to information on how to make applications global.<br>
</p>
<h2><a name="SubmittingComments">Submitting Comments, Requesting Features
and Reporting Bugs</a></h2>
<p>To submit comments, request features and report bugs, please contact
us. While we are not able to respond individually to each comment, we do
review all comments. Send Internet email to <a href=
"mailto:icu@oss.software.ibm.com">icu@oss.software.ibm.com</a>.</p>
<hr>
<p>Copyright © 1997-2000 International Business Machines Corporation
and others. All Rights Reserved.<br>
IBM Center for Emerging Technologies Silicon Valley,<br>
10275 N De Anza Blvd., Cupertino, CA 95014<br>
All rights reserved.</p>
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