private void Octal_Click(object sender, EventArgs e)
{
  const int max = 32;
  int[] a = new int[max];
  int num = Convert.ToInt32(textBox1.Text, 10);
  int i = 0;
  while (num > 0)
  {
       a[i] = num % 8;
       num /= 8;
       i++;
   }
   label2.Text =" Octal is " ;
   for (int j = i - 1; j >= 0; j--)
      label2.Text = label2.Text + a[j].ToString();
}
