C#

private void SetReadOnly(Control parent, bool readOnly)
{
  if (c != null)
  {
    foreach (Control child in parent.Controls)
    {
      if (child is TextBox)
      {
        TextBox tb = (TextBox)tb;
        tb.BackColor = Color.AliceBlue;
        tb.ReadOnly = readOnly;
      }
      // Recursively call with child controls' Controls
      SetReadOnly(child, readOnly);
    }
  }
}

SetReadOnly(Page, false);

//foreach(WebControl ctr in Page.Controls)
foreach(Control ctr in Page.Controls)
{
    if(ctr.GetType().Equals(GetType(TextBox)))
    {
        TextBox t = (TextBox)ctr;
        t.BackColor = Color.AliceBlue;
        t.ReadOnly = false;
    }
}

using System;
using System.Windows.Forms;

public class Test : Form
{
	static void Main()
	{
		Application.Run(new Test());
	}
	
	protected override void OnKeyDown(KeyEventArgs e)
	{
		base.OnKeyDown(e);
		Console.WriteLine(e.KeyCode);
	}
}

public struct Phone
{
  public int CountryCode;
  public int AreaCode; // It's better to use properties, but this is an example
  public string Number;
  public static Phone Parse(string value)
  {
    // Assuming it's the right format.
    Phone p = new Phone();
    int index = 0;
    p.CountryCode = int.Parse(value.Substring(0, 1); index += 1;
    p.AreaCode = int.Parse(value.Substring(index, 3); index += 3;
    p.Number = value.Substring(index, 7);
  }
}