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Sourcecode: qt4-x11 version File versions

bool QString::isNull (  )  const [inline]

Returns true if this string is null; otherwise returns false.

Example:

snippets/qstring/main.cpp Widget::isNullFunction() QString().isNull() QString("abc").isNull()

Qt makes a distinction between null strings and empty strings for historical reasons. For most applications, what matters is whether or not a string contains any data, and this can be determined using the isEmpty() function.

See also:
isEmpty()

Definition at line 462 of file qstring.h.

Referenced by Q3ActionGroup::add(), Q3Header::addLabel(), clear(), QDBusConnection::connect(), QDomImplementation::createDocumentType(), QAbstractFileEngineIterator::currentFilePath(), Q3TextDrag::decode(), QDBusConnection::disconnect(), Q3FileDialog::done(), QMotifStyle::drawControl(), QLineEdit::dropEvent(), Q3DataTable::find(), Q3ListBox::focusInEvent(), Q3FileDialog::getExistingDirectory(), Q3NetworkProtocol::getNetworkProtocol(), Q3FileDialog::getOpenFileName(), Q3FileDialog::getOpenFileNames(), Q3FileDialog::getSaveFileName(), Q3GDict::hashKeyString(), QComboBox::insertItem(), Q3ComboBox::internalHighlight(), Q3StyleSheet::item(), Q3ListView::keyPressEvent(), Q3Header::label(), QFont::lastResortFont(), QTranslator::load(), QLibraryInfo::location(), QFtp::login(), Q3Ftp::login(), Q3MimeSourceFactory::makeAbsolute(), Q3ListBox::mouseDoubleClickEvent(), operator<<(), QXmlStreamAttribute::operator==(), Q3TextEdit::optimAppend(), Q3TextEdit::optimSetText(), Q3ComboBox::paintEvent(), Q3Url::path(), QTextLayout::QTextLayout(), Q3ProgressDialog::setCancelButtonText(), QProgressDialog::setCancelButtonText(), Q3ListBox::setCurrentItem(), QUrl::setFragment(), Q3Header::setLabel(), QXmlNamespaceSupport::setPrefix(), Q3ListBox::setSelected(), Q3ListBox::takeItem(), and QXmlStreamWriter::writeProcessingInstruction().

{ return d == &shared_null; }


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