Enumerate all controls in ASP.NET Form

[Invoker]

Hi,

I need to enumerate all controls in a ASP.NET Form and make them read-only. In old VB6 I do it by following code:

Dim t As Control
For Each t In Form1.Controls
If TypeOf t Is TextBox Then
t.Locked = True
End If
Next

But how to do it in ASP.NET?