Looping through controls

Question

Hi, In my code I need to loop through the controls in a GroupBox and process the control only if it a ComboBox. I am using the code:

foreach (System.Windows.Forms.Control grpbxChild in this.gpbx.Controls)
{
    if (grpbxChild.GetType().Name.Trim() == "ComboBox")
    {
        // Process here
    }
}

My question is: Instead of looping through all the controls and processing only the combo boxes is is possible to get only the combo boxes from the GroupBox? Something like this:

foreach (System.Windows.Forms.Control grpbxChild in this.gpbx.Controls.GetControlsOfType(ComboBox))
{
    // Process here
}

Answer 1

Since you are using C# 2.0, you're pretty much out of luck. You could write a function yourself. In C# 3.0 you'd just do:

foreach (var control in groupBox.Controls.OfType<ComboBox>())
{
    // ...
}

C# 2.0 solution:

public static IEnumerable<T> GetControlsOfType<T>(ControlCollection controls)
    where T : Control
{
    foreach(Control c in controls)
        if (c is T)
            yield return (T)c;
}

which you'd use like:

foreach (ComboBox c in GetControlsOfType<ComboBox>(groupBox.Controls))
{
    // ...
}

Answer 2

if (!(grpbxChild is System.Windows.Forms.Combobox)) continue;

// do your processing goes here
grpbxChild.Text += " is GroupBox child";

Answer 3

Mehrdad is quite right, but your syntax (even if you are using C# 2.0) is overly complicated.

I find this to be simpler :

foreach (Control c in gpBx.Controls) 
{ 
  if (c is ComboBox) 
  { 
    // Do something.
  }
}

Answer 4

foreach (System.Windows.Forms.Control grpbxChild in this.gpbx.Controls)
{
    if (grpbxChild is ComboBox)
    {
        // Process here
    }
}

Answer 5

No Answer, just a thank you. This helped me resolve an issue I was fighting with, while using dynamically created radio buttons.