Validating user input visual basic
Validation is an easy way of requiring input in a specific text box without much hassle.
There is a control called Required Field Validator that automatically checks if a text box has input and will not validate if it doesn’t, preventing the user from submitting blank values.
Text(i)) = 0 Then Msg Box("Invalid telephone number.") txt Telephone.
If a user fails to put text in any of the text boxes, a red asterisk (the Required Field Validator) will appear next to the appropriate text box and the button won’t continue to the event handler until all text boxes have text.
Text End Sub End Class Save and run the application, it my ask to ‘Modify the Web.config file to enable debugging’, click OK.
For our Visual Basic applications, we will need to work a little harder to ensure that the input is valid, because we will need to define and code our own validation rules.
In a software project of any size, the task of determining what valid data is usually undertaken long before any code is written, and is part of an initial requirements analysis phase.