Searching URL String for Subdomain value

I have my DNS setup to answer for any subdomain. I need to be able to
look at the URL typed in like "joe.mysite.com" and put the subdomain
in a variable, so I can then look it up in a database. This would have
to work if they typed in http://joe.mysite.com or just joe.mysite.com.

Here is what I have started with, but as you can see I'm a little
stuck.

Sub ExtractDomain(ByVal expr As String)

Dim sURL As String = Page.Request.Url.ToString()
Dim subDomain = InStr(1, sURL, "http://")
If subDomain > 0 Then
'True so count over 7 characters


Else
'False, so start immediately


End If

End Sub

hi,
you should use regular expressions for this job, they are in their element
here.
you can use the expression [\w-]+ to match all the components of a URL.
for example, running Regex.Matches on http://joe.mysite.com will yield 4
captures in the first group:
http joe mysite com
you can then decide how you want to deal with them. you want to support
someone using HTTPS, and also a domain without a subdomain, such as
http://mysite.com or even http://mysite if running in an intranet
environment.
plenty of regex tutorials on the net and in the SDK docs if you need a
refresher on regex.
good luck
tim

"CSINVA" <mcse_instructor (AT) yahoo (DOT) com> wrote

I have my DNS setup to answer for any subdomain. I need to be able to
look at the URL typed in like "joe.mysite.com" and put the subdomain
in a variable, so I can then look it up in a database. This would have
to work if they typed in http://joe.mysite.com or just joe.mysite.com.

Here is what I have started with, but as you can see I'm a little
stuck.

Sub ExtractDomain(ByVal expr As String)

Dim sURL As String = Page.Request.Url.ToString()
Dim subDomain = InStr(1, sURL, "http://")
If subDomain > 0 Then
'True so count over 7 characters


Else
'False, so start immediately


End If

End Sub

"CSINVA" <mcse_instructor (AT) yahoo (DOT) com> wrote

I have my DNS setup to answer for any subdomain. I need to be able to
look at the URL typed in like "joe.mysite.com" and put the subdomain
in a variable, so I can then look it up in a database. This would have
to work if they typed in http://joe.mysite.com or just joe.mysite.com.

Use System.Uri and the TryCreate method, then check the Host property.