int[,] a = new int[3,5]{{0,1,2,3,4},{10,11,12,13,14},{20,21,22,23,24}}; int[] b = new int[15]; int i = 0; foreach (int num in a) { b[i++] = num; } for (i = 0; i < b.Length; i++) Console.Write(b[i].ToString() + " "); Console.ReadKey();