Reference an object via string

Question

So say I have 10 buttons on my form named btn1, btn2, btn3, etc. And I want to set each of their text properties to something. So I do something like:

For i = 1 To 10
    //something like:
    ["btn" & i].text = 'blah' //hope you understand what I meant here
Next

Can this also be done with variables? Like I have var1, var2, var3, etc. And if I wanted to control each of them, can I do it in a loop and not one by one?

`Me.Controls("btn" & i.ToString()).Text` is close to what you want. alternatively store the name in a List or the control references themselves. Tun on `Option Strict` though `"btn" & i` is nonsense — Ňɏssa Pøngjǣrdenlarp, May 03 '15 at 23:45
possible duplicate of [Referencing an object using a variable string in Visual Basic 2010](http://stackoverflow.com/questions/3887878/referencing-an-object-using-a-variable-string-in-visual-basic-2010) — Enigmativity, May 04 '15 at 00:31
When I try the Me.Controls("btn" & i.ToString()).Text I get an exception: "Object reference not set to an instance of an object." — Aleksa Kojadinovic, May 04 '15 at 11:36
EDIT: I've just realized that it's not working even if I hardcore the string: me.controls("btn1").text = "asd" gives the same exception — Aleksa Kojadinovic, May 04 '15 at 11:38
While this is absolutely possible to achieve, it’s probably the worst possible solution. In your particular example, you should be putting the controls into an array/list instead. — Konrad Rudolph, May 04 '15 at 16:07
Okay I've decided to go with the dictionary method. It works for buttons but not for variables. I can retrieve the value but not change it. I have a dictionary called varDict(of String, integer), and within I have like 10 integer variables. If I wanted to change the value of one of those how would I do that? varDict("var1") = 5 doesn't work — Aleksa Kojadinovic, May 04 '15 at 16:27

score 0 · Answer 1 · edited May 23 '17 at 10:24

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To get the controls from a form look at this https://stackoverflow.com/a/3426721 it's c# but easy to understand.

edited May 23 '17 at 10:24

Community

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1

answered May 03 '15 at 23:47

Chalumeau

101
10

FYI GetNextControl() method of WinForms iterates over all controls including controls nested in containers. It only returns controls that can be tab stops. Not perfect - doesn't look into SplitContainer(), returns scrollbars, maybe other flaws. – rheitzman May 04 '15 at 15:49

score 0 · Answer 2 · answered May 04 '15 at 15:57

Note that the Controls() collection is a property of a Container. A Form is a container. If you have controls in a container on a form e.g. a TabControl the buttons on the TabControl are not in the parent form's Controls but in the TabControl.Controls.

    Dim container As Control = Me
    For i = 1 To 2
        container.Controls("Button" & i).Text = "blah2"
    Next

Reference an object via string

2 Answers2