C errorprovider validating
If the user enters invalid data they’ll see an icon shown in Figure 3.After the validating event returns without being cancelled, meaning we have valid user input, then the validated event will be raised.This solution is a C# Windows Forms application that contains a single form.On the form are eight different text boxes and each these text boxes are validated against a different set of criteria: Figure 3 (below) shows the solution explorer for the project.The project is entitled Use Error Provider; as can be seen in the figure, no additional references beyond the defaults were added to the project. The Project Code: Use Error Provider The application is very simple; in execution, when the application is started, the form will display eight text box controls.Each of the controls has an event handler defined for the "Validated" event.The code starts off with the default imports; in addition to the defaults, the Regular Expression library has also been added to the code in order to support the evaluation of one of the text boxes against a regular expression.
Here is just the validating event handler’s code: The event driven validation model in Win Forms is powerful and flexible enough to allow you to create high quality apps that implement robust and maintainable validation code in your forms.If the string is not empty, the error provider is set to display nothing; this disables the error provider as applied to that control.The result is that, whenever the text box control is validated, the test will execute and, if failed, the error provider icon will be displayed.Figure 1: Error Provider Control in Use Marking Bad Input To use an error provider control, merely drop one from the toolbox onto the form; you may use a single error provider control to mark any and all of the fields on a form, in this respect, using the error provider is similar to using the tool tip control.
Once the control has been placed on the form, it may be controlled programmatically.In the example provided, there is "Validate All" button that does test each of the controls on the form and mark any which contain invalid data.