CODEWITHSUNDEEP
c#winformsforeach
Fancy_Mammoth
Fancy_Mammoth

Reputation: 91

How does C# iterate through Form Controls in a Foreach loop

As in the title, my question is how does C# iterate through form controls in a foreach loop? In case that is a bit too vague I'll add a bit more detail:

When I do foreach(Control c in MyForm) how does it index(?) through the controls? Is it based on tab order or something else? Any assistance would be appreciated as I'm trying to find out if I can place values into an array in a neater and more organized fashion.

Upvotes: 1

Views: 1752

Answers (3)

ajawad987
ajawad987

Reputation: 4672

Are you referring to the order that the controls are iterated over? I want to say that the controls are iterated over in the order that they were added to the Form's control collection. You can check this in the InitializeComponents designer method to see the order the controls are listed in that method.

Upvotes: 0

Reza Aghaei
Reza Aghaei

Reputation: 125342

It doesn't return controls based on tab index, it returns the controls in the order you added them the Controls collection.

You can see this order in designer in Document Outline window. (Ctrl + Alt + T) and change the order by moving controls in tree in the Document Outline window. Also if you use Bring To front and Send To back toolbar buttons you can change this order in design time.

At run-time you can change this order by calling SendToBack and BringToFront method of controls or SetChildIndex method of Controls collection.

To get the index of a control, you can use GetChildIndex method of Controls collection.

Also keep in mind foreach(Control c in this.Controls) just will scan controls which you put directly on the form. For example if you have a panel on form and the panel contains some controls, children of panel are in panel.Controls collection and not in controls collection of form.

Upvotes: 3

BradleyDotNET
BradleyDotNET

Reputation: 61379

foreach always works the same, so doing it over a form's controls doesn't change anything.

It doesn't really use an index either; foreach only works on instances of classes that implement IEnumerable which means they have a GetEnumerator method. foreach uses the returned IEnumerator to go through the collection one at a time; order is dependent on the actual implementation.

For List (or any array) this is in-order (ie index 0 is first, 1 second, and so on); for a random implementation of IEnumerable you would have to look at the source. In your specific example, look at the type of the Controls collection on Form. Its a ControlCollection so you'll want to look on Reference Source to find how it enumerates.

Based on the implementation it appears to be in-order with some safeguards against controls being removed during enumeration.

Upvotes: 4

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