private void button1_Click(object sender, RoutedEventArgs e)       {           int[] copy1 = { 1, 2, 3, 4 };           int[] copy2 = { 5, 6, 7, 8 };           int[] copy3 = new int[copy1.Length + copy2.Length];           copy1.CopyTo(copy3, 0);           copy2.CopyTo(copy3, 4);       }