C#: Can I have a method return IEnumerator<T> and use it in a foreach loop?

Howdy,

I need to set the height of every textbox on my form, some of which are nested within other controls. I thought I could do something like this:

private static IEnumerator<TextBox> FindTextBoxes(Control rootControl)
{
    foreach (Control control in rootControl.Controls)
    {
        if (control.Controls.Count > 0)
        {
            // Recursively search for any TextBoxes within each child control
            foreach (TextBox textBox in FindTextBoxes(control))
            {
                yield return textBox;
            }
        }

        TextBox textBox2 = control as TextBox;
        if (textBox2 != null)
        {
            yield return textBox2;
        }
    }
}

Using it like this:

foreach(TextBox textBox in FindTextBoxes(this))
{
    textBox.Height = height;
}

But of course the compiler spits its dummy, because foreach expects an IEnumerable rather than an IEnumerator.

Is there a way to do this without having to create a separate class with a GetEnumerator() method?

Am I mad?

Anthony

From stackoverflow littlecharva

• As the compiler is telling you, you need to change your return type to IEnumerable. That is how the yield return syntax works.

  Timwi : `yield return` can be used with methods that return *either* `IEnumerable` *or* `IEnumerator`. It’s only in the `foreach` loop where `IEnumerator` can’t be used.
  From Ch00k

• // Generic function that gets all child controls of a certain type, 
  // returned in a List collection
  private static List<T> GetChildTextBoxes<T>(Control ctrl) where T : Control {
    List<T> tbs = new List<T>();
    foreach (Control c in ctrl.Controls) {
      // If c is of type T, add it to the collection
      if (c is T) { 
        tbs.Add((T)c);
      }
    }
    return tbs;
  }
  
  private static void SetChildTextBoxesHeight(Control ctrl, int height) {
    foreach (TextBox t in GetChildTextBoxes<TextBox>(ctrl)) {
      t.Height = height;
    }
  }
  

  From Yaakov Ellis

• I can't believe it was that simple, thanks.

  Timwi : Please delete this answer because it is not an answer. Thanks!
  From littlecharva

• If you return IEnumerator, it will be a different enumerator object each time call that method (acting as though you reset the enumerator on each iteration). If you return IEnumerable then a foreach can enumerate based on the method with the yield statement.

  From Joseph Daigle

• Just to clarify

  private static IEnumerator<TextBox> FindTextBoxes(Control rootControl)
  

  Changes to

  private static IEnumerable<TextBox> FindTextBoxes(Control rootControl)
  

  That should be all :-)

  From Orion Edwards