Update In Linq

http://stackoverflow.com/questions/3658028/linq-to-objects-update

 

And I write a code example to test perfomence.

class Program
    {
        static void Main(string[] args)
        {
            List<Person> source = Generate(10000, (c) =>
            {
                return c * 10;
            });


            List<Person> target = Generate(10000, (c) =>
            {
                return c * 20;
            });

            CodeTimer.Initialize();
            CodeTimer.Time("UseLinq", 1, () => { UseLinq(source, target); });
            CodeTimer.Time("UseList", 1, () => { UseList(source, target); });

            //foreach (var s in source)
            //{
            //    Console.WriteLine(string.Format("Person's Id is {0}, Age is {1}", s.Id, s.Age));
            //}
            Console.ReadLine();
        }



        static void UseLinq(List<Person> source, List<Person> target)
        {
            Func<Person, Person, Person> updateFunc = (s, t) => { s.Age = t.Age; return s; };
            var update = (from s in source
                          join t in target on s.Id equals t.Id
                          select updateFunc(s, t)).ToList();
        }

        static void UseList(List<Person> source, List<Person> target)
        {
            foreach (Person s in source)
            {
                Person p = target.SingleOrDefault(t => t.Id == s.Id);
                if (p != null)
                {
                    s.Age = p.Age;
                }
            }
        }

        static List<Person> Generate(int num, Func<int, int> age)
        {
            List<Person> list = new List<Person>();
            for (int i = 0; i <= num; i++)
            {
                Person p = new Person();
                p.Id = i;
                p.Age = age(i);
                list.Add(p);
            }
            return list;
        }

 

The result is: