Ref on a list not changing values
c#, list, object
Solution
Looks like you are adding same instance of unit many times to list. Thus all list items point to single object in memory. Modifying any item modifies that object.
List<IUnit> army = new List<IUnit>();
Infantry infantry = new Infantry();
for(int i = 0; i < 10; i++)
{
// adds same instance each time
army.Add(infantry);
}
You should instantiate new unit when adding units to list. E.g.
List<IUnit> army = new List<IUnit>();
for(int i = 0; i < 10; i++)
{
// create new instance each time
Infantry infantry = new Infantry();
army.Add(infantry);
}
BTW you don't need `ref` here:
public void ShotRandomGuy(List<IUnit> army)
{
Random r = new Random();
var unit = army[r.Next(army.Count)];
unit.HealthPoints -= 25;
}
Problem
I'm moving over from Java to C#, and been coding some example programs. Now I have come across a List of different objects (IUnit) and when I make a call to a certain value in the list to change it's value, it changes all the values. I have added a reference to the List - As per other Stack overflow questions. So I have the following classes ``` interface IUnit { int HealthPoints { set; get; } String ArmyType { get; } } ``` This is the base class I call to create a list of Army Types (Marines/Infantry). The implementation is the same expect a change to the values inside the class. ``` public class Infantry : IUnit { private int health = 100; protected String armyType = "Infantry"; public int HealthPoints { get { return health; } set { health = value; } } public String ArmyType { get { return armyType; } } ``` I then initialize the List with the following code ``` List<IUnit> army = new List<IUnit>(); Infantry infantry = new Infantry(); Marine marine = new Marine(); army.Add(Marine); ``` Then I have a method, which just takes away 25 from the health points. ``` public void ShotRandomGuy(ref List<IUnit> army) { army[0].HealthPoints = army[0].HealthPoints - 25; } ``` I then call that method as shown below. ``` battle.ShotRandomGuy(ref army); ``` However it takes the 25 away from all the Objects in that List. How would I stop it doing that? I have added a reference to the List, so I would of thought it would of taken it away from the the original List. Do I need to clone the list? Would that work? Or is it more of a design issue? Thank you!