using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace ForEachDemo{    class Program    {        static void Main(string[] args)        {            Console.WriteLine(LambdaAndEach()); //输出：‘1‘,‘4‘,‘5‘,‘6‘,‘7‘,‘8‘,‘9‘,‘10‘            Console.ReadKey();        }        public static string LambdaAndEach()        {            //数据源            var retList = new List<int>() { 1, 4, 5, 6, 7, 8, 9, 10 };            var sbBuilder = new StringBuilder();            retList.ForEach(item =>            {                //如果是最后一个元素则用(‘item‘)包裹，否则用(‘item‘,)包裹元素                if (item == retList[retList.Count - 1])                {                    sbBuilder.Append("‘" + item + "‘");                }                else                {                    sbBuilder.Append("‘" + item + "‘,");                }            });            return sbBuilder.ToString();        }    }}

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace ConsoleApplication1{    class User    {        public Guid Id { get; set; }        public string UserName { get; set; }        public string Pwd { get; set; }    }    class Program    {        static void Main(string[] args)        {            //数据源            var dataSource = new List<User>()            {                new User() {Id = Guid.NewGuid(), UserName = "admin", Pwd = "123"},                new User() {Id = Guid.NewGuid(), UserName = "zhang", Pwd = "345"},                new User() {Id = Guid.NewGuid(), UserName = "liu", Pwd = "999"}            };            var uids = dataSource.Select(u => u.Id.ToString());            Console.WriteLine("所有用户ID,用空格|隔开\n{0}", string.Join(" | ", uids));            //输出：所有用户ID,用空格|隔开            //44927238 - 8ce7 - 4581 - 91ec - 4797712dc85a | 116037c7 - 4275 - 4491 - 9a2a - afb887ea2cf0 | 2c157abc - 8f13 - 4394 - b5e3 - 4778a9a420df            Console.ReadKey();        }    }}