14.2. Validators

Validators are objects that can be attached to input widgets (such as QLineEdit, QSpinBox, and QComboBox) to provide a general framework for checking user input. Qt has an abstract class named QValidator that establishes the interface for all built-in and custom validators.

Two of QValidator’s concrete subclasses can be used for numeric range checking: QIntValidator and QDoubleValidator. There is also a concrete subclass that can be used for validating a string with a specified regular expression. We discuss regular expressions in the next section.