C#

public static List<T> GetControlsInTree<T>(Control parent) where T: Control {
 List<T> result = new List<T>
 AddControlsInTree(parent, result);
 return result;
}

static void AddControlsInTree<T>(Control parent, List<T> list) where T: Control {
 foreach (Control c in parent.Controls){
  T t = c as T;
  if (t != null) list.Add(t);
  AddControlsInTree(c, list);
 }
}

List<PictureBox> pictures = GetControlsInTree<PictureBox>(this);

private void ResetPictureBoxes()
 foreach(PictureBox picture in pictures)
  picture.BackgroundImage = Resource1.island;
}

public String ConvertToBase(int num, int nbase)
        {
            String chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

            // check if we can convert to another base
            if (nbase < 2 || nbase > chars.Length)
                return "";

            int r;
            String newNumber = "";

            // in r we have the offset of the char that was converted to the new base
            while (num >= nbase)
            {
                r = num % nbase;
                newNumber = chars[r] + newNumber;
                num = num / nbase;
            }
            // the last number to convert
            newNumber = chars[num] + newNumber;

            return newNumber;
        }

const string chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
static readonly int num_chars = chars.Length;

static string NumberToCode(int number)
{
  if (number < 0 || number > num_chars * num_chars)
    throw new ArgumentOutOfRangeException();

  return chars[number / num_chars].ToString() + chars[number % num_chars];
}

static public string EncodeTo64(string toEncode)
{
    byte[] toEncodeAsBytes = System.Text.ASCIIEncoding.ASCII.GetBytes(toEncode);
    string returnValue = System.Convert.ToBase64String(toEncodeAsBytes);
    return returnValue;
}

static public string DecodeFrom64(string encodedData)
{
    byte[] encodedDataAsBytes = System.Convert.FromBase64String(encodedData);
    string returnValue = System.Text.ASCIIEncoding.ASCII.GetString(encodedDataAsBytes);
    return returnValue;
}