static void Main(string[] args) { Console.WriteLine("Welcom to Array Land!"); ArrayClass print1 = new ArrayClass(); int[] intArray1 = new int[3] { 1, 3, 5 }; int[] intArray2 = new int[3] { 2, 4, 6 }; //int[] sumArray = new int[intArray1.Length * intArray2.length]; (don't need, as it's declared in the class method) sumArray = print1.AddTheArrays(intArray1, intArray2); Console.ReadLine(); }