To start, we create a text field and bring up the properties dialog for the field.
Then we select the “Validate” tab to see the validation options: The default is that the field will not get validated.
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. Again, certain special characters are obviously not allowed.
You could say that a program's testers are supposed to do this; yes, they should - nobody else should. If not, if there is even just one unallowed character that is not supposed to be there, the Match method will return False. Instead of you having to loop through each character to determine what that character is, you simply need the correct Regular Expression pattern. Clear() Surname Valid = False Else Surname Valid = True End If End Sub It is basically the exact same code for the Name box, but I just included the capability to comprehend a space character as well. People expect to enter a phone number in a format similar to this: ###-###-####.
Well, sometimes a good structured and thought out If statement can suffice, but it can become quite long and cumbersome in the future. By using Regular Expressions this way, you can reduce the chances of getting errors at erratic times. This sub checks the email's format and if it thinks that it matches, it returns True and vice versa.
Also, the more tests you are performing, the slower your app might become. For more information regarding Regular Expressions, you are welcome to look at these two MSDN articles: Because 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. NET application and design the form to resemble Figure 1. Obviously this only works for the formatting of the email.
So, what I am trying to say is: make sure you understand other cultures, or be aware of people with uncommon names. Using Regular expressions here, is basically the standard, even though it is a bit messy. Focus() 'Return Focus End If End Sub Here, I created a separate function to do all the work.
Add this to validate the surname textbox: Private Sub txt Surname_Leave(sender As Object, e As System. Leave 'Create A Pattern For Surname Dim str Surname As String = "^[a-z A-Z\s] $" Dim re Surname As New Regex(str Surname) 'Attach Pattern To Surname Textbox 'Not A Match If Not re Surname. Add the following code to validate your phone number textbox: 'Function To Check Phone Number Validity Public Function Validate Phone(By Val str Phone Num As String) As Boolean ''Create Reg Exp Pattern Dim str Phone Pattern As String = "^[1-9]\d-[1-9]\d-\d$" 'Create Reg Ex Object Dim re Phone As New Regex(str Phone Pattern) 'Something Typed In If Not String. This function is later called inside the textbox's Lost Focus event, which also fires when a control loses the focus. Keep in mind that each country has its own domain name, which sometimes will look like: Private Sub Validate Email() 'Set Up Reg Exp Pattern To Allow Most Characters, And No Special Characters Dim re Email As Regex = New Regex("([a-z A-Z0-9_\-\.] )@((\[[0-9]\.[0-9]\.[0-9]\." _ ")|(([a-z A-Z0-9\-] \.) ))([a-z A-Z]|[0-9])", _ Regex Options.