Qt validating user input
Qt emulates the look and feel of Motif, but is much easier to use.Best of all, after you have written an application with Qt, all you have to do is recompile it to have a version that works on Windows. You'll find that you need to write very little, if any, platform-dependent code because Qt already has what you need.For example, an ISBN validator might want to delete every character except digits and "-", even if the result is still not a valid ISBN; a surname validator might want to remove whitespace from the start and end of the string, even if the resulting string is not in the list of accepted surnames. The locale is by default initialized to the same as QLocale(). Sets the locale that will be used for the validator.Unless set Locale has been called, the validator will use the default locale set with QLocale::set Default().
This function attempts to change input to be valid according to this validator's rules.
Here are some examples: fixup() is provided for validators that can repair some user errors. QLine Edit, for example, will call fixup() if the user presses Enter (or Return) and the content is not currently valid. For example, QInt Validator and QDouble Validator use it to parse localized representations of integers and doubles.
This allows the fixup() function the opportunity of performing some magic to make an Invalid string Acceptable. QValidator is typically used with QLine Edit, QSpin Box and QCombo Box. The parent parameter is passed on to the QObject constructor.
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.
The function can change both input and pos (the cursor position) if required. Documentation contributions included herein are the copyrights of their respective owners.