![]() ![]() You could say that a program’s testers are supposed to do this yes, they should – nobody else should.Īdd the following inside your name Textbox’s Leave event: Private Sub txtName_Leave(sender As Object, e As System.EventArgs) Handles txtName.Leave Sometimes people are just trying to be funny, or they are literally trying to break your program. That may seem like Captain Obvious speaking, but you’ll be amazed at some of the data that gets entered into a name field. Validating NamesĪ name doesn’t generally contain weird symbols, and definitely not numbers. Based on each of these variables’ values, we will know if the data is correct or not. These objects will determine if all our data is valid or not. Private EmailValid As Boolean 'Is Email Valid? Private PhoneValid As Boolean 'Is Phone Number Valid? Private SurnameValid As Boolean 'Is Surname Valid? The Regular Expression’s functionalities exist in the namespace, so let us add that first: Imports ' Regular Expressions NamespaceĪdd the following four variables inside the General Declarations section: Private NameValid As Boolean 'Is Name Valid? Start Visual Studio and create a Desktop VB.NET application and design the form to resemble Figure 1. Regular Expression Language – Quick Reference.īecause it is always easy to learn by doing things practically, you will be creating an app that makes use of Regular Expressions to determine valid input.By using Regular Expressions this way, you can reduce the chances of getting errors at erratic times.įor more information regarding Regular Expressions, you are welcome to look at these two MSDN articles: This means that as a programmer, you have the power to supply the exact pattern for the input you desire in any text input field. They make use of a pattern matching system to match the input with a certain pattern of data. Regular Expressions are extremely powerful. So what can we do? The answer is simple: Use Regular Expressions! That is what they were invented for. ![]() Also, the more tests you are performing, the slower your app might become. Well, sometimes a good structured and thought out If statement can suffice, but it can become quite long and cumbersome in the future. There are some more tests, but I want to keep this article straightforward and basic enough. For example : If you are only supposed to type in 50 characters, you must not be able to enter more than fifty.
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