[tvqpriqphh]

The code sample doesn't describe a control array, rather "programmatic addressing". This code snippet does exactly the same thing (in a less rediculous fashion):

select case txtwhotext.text
    case "1"
        textbox1.text = "1"
    case "2"
        textbox2.text = "2"
    case "3"
        textbox3.text = "3"
    case "4"
        textbox4.text = "4"
end select

if you want an array of controls, try something like this:

' this is a class/form instance variable
' use nothing as a place holder for element zero in the zero based array
dim ca as control() = new control() {nothing, textbox1, textbox2, _
textbox3, textbox4}

sub dosomething()
    ' get the user specified index
    dim index as integer = cint(textwhotext.text)

    ' put the user specified message into that textbox
    ca(index).text = textwhotext.text

end sub

note that this really only gets you halfway home -- you now have a way to translate an integer index into a control object reference -- how do you convert a control object reference into an integer index?

function getindex(c as control) as integer
    for i as integer = 1 to ca.length-1
        if c is ca(i) then
            return i
        end if
    next
    throw new applicationexception("control reference not found")
end function

now we can have "control array" based events like this (having to manually bind events makes maintaining this code a bit ugly)

sub click_handler(sender as object, ea as eventargs) handles _
textbox1.click, textbox2.click, textbox3.click, textbox4.click
    dim i as integer = getindex(sender)
    ca(i).text = "you clicked me"

end sub

note that .net sort of obsoletes the need for control arrays, because you could just have easily defined click_handler as follows:

sub load
    addhandler textbox1.click, addressof (click_handler)
    addhandler textbox2.click, addressof (click_handler)
    addhandler textbox3.click, addressof (click_handler)
    addhandler textbox4.click, addressof (click_handler)

end sub

sub click_handler(sender as object, ea as eventargs)
    ctype(sender, control).text = "you clicked me"

end sub