using System;

using System.Collections.Generic;

using System.Linq;

public class Cat

        {

        public string name {get;set;}

        public int age {get;set;}   

        }

​

public class Program

{

    public static void Main()

    {

        int catAge = 0;

    List<Cat> cats = new List<Cat>();

        var catCalledBrian = cats.Where(x => x.name == "Brian").FirstOrDefault();

        int? briansAge = catCalledBrian != null ? (int?)catCalledBrian.age : null;

        if(catCalledBrian != null)

        {

     catAge = catCalledBrian.age;

            }

    Console.WriteLine(catAge);

        /*

        Sorry, I got confused about the Elvis operator; that’s this right: ?.

What it does is let you reference an object, even if it is null, without causing an exception. If the left-hand side is null then it will immediately return null.

Dog dog = new Dog() { Owner = null };

string ownerName = dog.Owner?.Name;

because dog.Owner is null, the statement terminates here dog.Owner?.Name and immediately gives you null – otherwise you would have NullRefException on trying to access the Name. You can chain these and it will stop at the first null item

Dog dog = null;

String ownerName = dog?.Owner?.Name;

And you can pair this with the ?? as well to give you a “default” value if the left is null

String ownerName = dog?.Owner?.Name ?? “Bob”;

        */

    }

}