How do I create an array of objects in constructor?

Question

I have two classes:

game

element

I want to be able to define an array of element objects in a game object. When I try this I get the warning message "..is never assigned to, and will always have its default value null"; in the local variables in the debugger I can see that the array exists, but all entries are null. The class Element works as I would expect. If I assign element objects to an array in Main it works, but not when I move the code to the Game constructor.

What am I doing wrong? I'm new to C# so it could be something very basic. Code below. Many thanks.

class Element
 {
 public Element()
 {
 elements = new List<int>(3);
 elements.Add(1);
 elements.Add(2);
 elements.Add(3);
 }
 List<int> elements;
 public void PrintElement()
 {
 for (int i = 0; i < 3; i++)
 {
 Console.WriteLine("Element {0}: {0}", i + 1, elements[i]);
 }
 }
 }
class Game
 {
 public Game()
 {
 Element1 = new Element();
 Element2 = new Element();
 Element3 = new Element();
 Element[] ThisGame = new Element[3];
 ThisGame[0]= Element1;
 ThisGame[1] = Element2;
 ThisGame[2] = Element3;
 }
 public Element[] ThisGame;
 private Element Element1;
 private Element Element2;
 private Element Element3;
 public void PrintGameElement(int number)
 {
 ThisGame[number].PrintElement();
 }
 }
 class Program
 {
 Game MyGame;
 static void Main(string[] args)
 {
 Game MyGame = new Game();
 MyGame.PrintGameElement(2);
 Console.Read();
 }
 }

Answer 1

In Game, you are re-declaring ThisGame.

Change

Element[] ThisGame = new Element[3];

to

ThisGame = new Element[3];

Answer 2

Your Game constructor should look like this:

 public Game()
 {
 Element1 = new Element();
 Element2 = new Element();
 Element3 = new Element();
 ThisGame = new Element[3];
 ThisGame[0]= Element1;
 ThisGame[1] = Element2;
 ThisGame[2] = Element3;
 }

Answer 3

You need to set the list object to something when you initialize it.

List<int> elements = null; 

OR

List<int> elements = new List<int>(); 

• James Johnson: Yes, but where he declares his list object, it is not set to anything, which will cause this warning.

Answer 4

look at this code it may help you to make some order in your code:

Element class :

class Element
 {
 //property on element to save element data
 public string ElementData { get; set; }
 public Element(string data)
 {
 ElementData = data;
 }
 }

Game class :

class Game
 {
 //property on Game to save all elements
 Element[] Elements { get; set; }
 public Game(Element[] elements)
 {
 Elements = elements;
 }
 public void PrintGameElements()
 {
 foreach (var element in Elements)
 {
 Console.WriteLine(element.ElementData);
 }
 }
 public void PrintElement(int index)
 {
 Console.WriteLine(Elements[index].ElementData);
 }
 }

Main function that initialize the array and pass it to the game :

static void Main(string[] args)
 {
 //initialize the array 
 var elements = new[]
 {
 new Element("data x"),
 new Element("data y"),
 new Element("data z")
 };
 //pass the elements to the game
 var game = new Game(elements);
 //print the second element
 game.PrintElement(1);
 //print all elements
 game.PrintGameElements();
 Console.ReadKey();
 }
 }