using System;

using System.Linq;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        var myArray = new [] {

            new TestObject {

                Id = 1,

                Name = "First",

            },

            new TestObject {

                Id = 2,

                Name = "Second",

            }

        };

        var toUpdate = myArray.First(a => a.Id == 2);

        toUpdate.Name = "Updated";

        foreach (var o in myArray) {

            Console.WriteLine($"Id: {o.Id}, Name: {o.Name}");

        }

    }

    public class TestObject

    {

        public long Id {get;set;}

        public string Name {get;set;}

    }

}