CODEWITHSUNDEEP
c#arraysreference
Nathanaël Radomír
Nathanaël Radomír

Reputation: 21

How to change an array object without a reference to the array?

Let's say that I have an object of type A at index 5 of array items and I want to change it to be a new object of type B.

If I had a reference to the array, I could just do items[5] = new B(); to change the item.

However, let's suppose that I only had the object at items[5] and not the reference to the array, and it's stored in a variable item. If I just do item = new B();, the change will not be reflected in the array, because only that variable will be changed.

Is it possible to change that item in such a way that the change will be reflected in the array, such that items[5] will contain that new item of type B?

Preferably something simple without the use of delegates or lambdas or the like because it is somewhat performance-critical.

Upvotes: 2

Views: 105

Answers (1)

Jenish Rabadiya
Jenish Rabadiya

Reputation: 6766

I believe in this case you should use ref.

Demonstrating example: 

public class Program
{
    public static void Main()
    {
        var list = new  List<Sample>();
        list.Add(new SampleDerived(){ Age=2, DAge = 5 });
        list.Add(new SampleDerived(){ Age=3, DAge = 5 });
        list.Add(new SampleDerived(){ Age=4, DAge = 5 });
        list.Add(new SampleDerived(){ Age=5, DAge = 5 });
        list.Add(new SampleDerived(){ Age=6, DAge = 5 });
        var list2 = list.ToArray();
        Process(ref list2[2]);
        Console.WriteLine(list2[2].Age); // will print 10 not 4
    }

    public static void Process(ref Sample s)
    {
        s = new Sample(){Age=10};
    }
}
public class Sample
{
    public int Age {get; set;}
}

public class SampleDerived : Sample
{
    public int DAge {get; set;}
}

Dot net fiddler is here.

Upvotes: 1

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