Information about Unicode on the web. The Unicode Consortium has a number of documents available, including
The Standard. The current version of the standard is 3.0.0.
As used in Qt. In Qt, and in most applications that use Qt, most or all user-visible strings are stored in Unicode, and Qt provides
To obtain the benefits of Unicode, we recommend using QString for storing all user-visible strings and do all text file I/O using QTextStream. Use QKeyEvent::text() for keyboard input in any custom widgets you write; it does not make much difference for slow typists in West Europe or North America, but for fast typists or people using special input methods using text() is beneficial.
All the function arguments in Qt that may be user-visible strings, QLabel::setText() and a thousand others, take
as type. QString provides implicit casting from
* such that things like
myLabel->setText( "Hello, Dolly!" );
will work. There is also a function, QObject::tr(), that provides translation support, like this:
myLabel->setText( tr("Hello, Dolly!") );
tr(), oversimplifying a bit, maps from
* to a
Unicode string, and uses installable QTranslator objects to do the
Turning back to Unicode, for programs that needs to talk to other programs or read/write files in legacy file formats, Qt provides a number of built-in QTextCodec classes, that is, classes that know how to translate between Unicode and a legacy encoding.
By default, conversion to/from
* uses a
locale-dependent codec. However, the program can easily find codecs
for other locales, and set any open file or network connection to use
a special codec. It is also possible to install new codecs, for
encodings that the built-in ones do not support. (At the time of
writing, Vietnamese/VISCII is one example of that.)
Since US-ASCII and ISO-8859-1 are so common, there are also specially fast functions for mapping to and from them. For example, to open an application's icon one might do this:
QFile f( QString::fromLatin1("appicon.png") );
Regarding output, Qt will do a best-effort conversion from Unicode to whatever encoding the system and fonts provide. Depending on operating system, locale, font availability and Qt's support for the characters used, this conversion may be good or bad. We aim to extend this in upcoming versions, with emphasis on the most common locales first.
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Qt version 2.3.10