使用Linq查找重复

namespace RemoveTheSame
{
    class Program
    {
        static void Main(string[] args)
        {
            List<User> list = new List<User>()
            {
                new User{Id=1,Name="user1",Pwd="123"},
                new User{Id=2,Name="user1",Pwd="123"},
                new User{Id=3,Name="user2",Pwd="123"}
            };
            GetTheSame(list, out string tkey);
            Console.WriteLine($"The Same is {tkey}");
            Console.ReadKey();
        }
        public static void GetTheSame(List<User> listOld, out string tkey/*,out User user*/)
        {
            tkey = null;
            var result = from x in listOld
                         group x by x.Name into g
                         where g.Count() > 1
                         select g;
            foreach (var item in result)
            {
                tkey = item.Key;
            }
        }
    }
    public class User
    {
        public string Name { get; set; }
        public int Id { get; set; }
        public string Pwd { get; set; }

    }
}


其实就是一行代码解决的问题~

list.GroupBy(x => x.Name).Where(x => x.Count() > 1).ToList().ForEach(x => Console.WriteLine(x.Key));