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How to validate textbox for email in vb.net
I have vb.net windows form.
A textbox txtemail is there.
The email is optional.
But i want once email is being entered it should validate correct email address.
A textbox txtemail is there.
The email is optional.
But i want once email is being entered it should validate correct email address.
Asked:
1 Solution
how about this link?
http://dotnetdud.blogspot.com/2008/06/vbnet-regular-expression-to-check-email.html
http://dotnetdud.blogspot.com/2008/06/vbnet-regular-expression-to-check-email.html
You can use Regex
Dim ErP As New ErrorProvider
If TextBox1.Text <> "" Then
Dim rex As Match = Regex.Match(Trim(TextBox1.Text), "^([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,3})$", RegexOptions.IgnoreCase)
If rex.Success = False Then
ErP.SetError(TextBox1, "Please Enter a valid Email-Address")
Else
ErP.SetError(TextBox1, String.Empty)
End If
End If
Ah the age old question: "How do I validate email addresses..." You can really only validate structure. There is no way in code to tell if an email address is valid or not. Even if you attempt to send a message, the server is the entity which will receive the response. If for some reason you need to know whether or not the actual address is "live", then you will need to come up with some scheme to verify (maybe check against AD if you are on a LAN).
As far as checking structure, the typical solution is to run the value against a regular expression (regex). In the link I referenced, you will see a few different examples of expressions you might use. Each has benefits and drawbacks. If you decide to use regex for this purpose, then whichever pattern you use, you can use logic such as this to validate the address:
Again, the regex approach only validates structure. It cannot tell you whether or not an account, or even a domain exists.
As far as checking structure, the typical solution is to run the value against a regular expression (regex). In the link I referenced, you will see a few different examples of expressions you might use. Each has benefits and drawbacks. If you decide to use regex for this purpose, then whichever pattern you use, you can use logic such as this to validate the address:
Dim emailIsValid As Boolean = System.Text.RegularExpressions.Regex.IsMatch(txtEmail.Text, "[pattern you chose]")
Again, the regex approach only validates structure. It cannot tell you whether or not an account, or even a domain exists.
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Imports System.Text.RegularExpress
Function EmailAddressCheck(ByVal emailAddress As String) As Boolean
Dim pattern As String = "^[a-zA-Z][\w\.-]*[a-zA-Z0
Dim emailAddressMatch As Match = Regex.Match(emailAddress, pattern)
If emailAddressMatch.Success Then
EmailAddressCheck = True
Else
EmailAddressCheck = False
End If
End Function