Question

I have a simple Class that I thought I could make more useful if I added a list property to store some values ( i dont want an array bc I dont know how long it will be)

public class MyClass
{
public double myProperty1;
public double myProperty2;
//etc
public  List<double> myList {get; set;}


}

but when I try to access this property, for example by

if x >y

newObject.myList.Add(x);

I get an error. Object reference not set to an instance of an object.

Any ideas what I am doing wrong here.

Answer 1

public class MyClass
{

    public double myProperty1;
    public double myProperty2;
    //etc
    public  List<double> myList {get; private set;}  // private set

    public MyClass()    // constructor
    {
           myList = new List<double>();    // create the list
    }
}

Your class instances need an actual List<> instance. The right place to create it is in a constructor. The private setter is usually a good idea but not essential.