say I have a textbox with attribute id="test_1"

How could I reference this id if I am in a loop

ex.
Code:
for i as Integer = 0 to 5
' I would like to give this textbox a value, I thought I could do something like
   Eval("test_" & i).Value = "someValue"
' but that did not work, I also tried to do 
  dim tmpTB as Textbox = Ctype("test_" & i, TextBox)
    
Next
Is there a way to do this?

bsw