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_\-\.] )@((\
Is Match(str Phone Num) 'Check Validity Else Phone Valid = False 'Not Valid / Empty End If Return Phone Valid 'Return True / False End Function Private Sub txt Tel_Lost Focus(sender As Object, e As System. If it isn't valid input, it will clear the textbox and give it the focus again; if it is valid, the Phone Valid variable gets updated to true.
Let’s assume when we click our save button that we wish to validate the controls and display an icon if there is a problem.
Each new exception can preserve the information about the previous one by storing it in this property.
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.
A network link to a server might fail just as you're transferring data.
Or perhaps you simply didn't allow for a particular rare circumstance in your code. NET Framework offers a robust set of tools for dealing with these unexpected problems.First, add the following code to the Form’s constructor after the Initialize Component method: This is a handy trick to prevent implicit validation of our controls when they lose focus.You do not have to disable the Form’s Auto Validate property.However, I prefer to call it explicitly and handle all validation at once since you most likely will take action only if the entire control’s children pass validation. The most important thing to recognize here is how precise you can be with the validation error message in the error provider.There are 2 code paths for validation failure, and in each case we provide the user with an appropriate error message. In a perfect world, your code would run correctly every time.