Qt validating user input
Qt and respective logos are trademarks of The Qt Company Ltd. All other trademarks are property of their respective owners.Qt Quick provides several types to display text onto the screen.Qt comes with excellent reference documentation, but beginners often find the included tutorial is not enough to really get started with Qt. You'll learn how to program in Qt as the book guides you through the steps of writing a simple paint application.Exercises with fully worked out answers help you deepen your understanding of the topics.
Unless set Locale has been called, the validator will use the default locale set with QLocale::set Default().
The book presents all of the GUI elements in Qt, along with advice about when and how to use them, so you can make full use of the toolkit.
For seasoned Qt programmers, there's also lots of information on advanced 2D transformations, drag-and-drop, writing custom image file filters, networking with the new Qt Network Extension, XML processing, Unicode handling, and more.
If the built-in validators aren't sufficient, you can subclass QValidator. Intermediate is less obvious: the concept of validity is difficult to apply when the string is incomplete (still being edited).
The class has two virtual functions: validate() and fixup(). It returns Invalid, Intermediate or Acceptable depending on whether its argument is valid (for the subclass's definition of valid). QValidator defines Intermediate as the property of a string that is neither clearly invalid nor acceptable as a final result.
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It need not result in a valid string: callers of this function must re-test afterwards; the default does nothing.