C#中的匿名函数、lambda表达式解读

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Test0630
{
    delegate void TestDelegate(string s);
    class Program
    {
        static void Main(string[] args)
        {
            // Original delegate syntax required 
            // initialization with a named method.
            TestDelegate testDelA = new TestDelegate(M);

            // C# 2.0: A delegate can be initialized with
            // inline code, called an "anonymous method." This
            // method takes a string as an input parameter.
            TestDelegate testDelB = delegate(string s) { Console.WriteLine(s); };

            // C# 3.0. A delegate can be initialized with
            // a lambda expression. The lambda also takes a string
            // as an input parameter (x). The type of x is inferred by the compiler.
            TestDelegate testDelC = (x) => { Console.WriteLine(x); };

            // Invoke the delegates.
            testDelA("Hello,this is TestA");
            testDelB("Hello,this is TestB");
            testDelC("Hello,this is TestC");

            // Keep console window open in debug mode.
            Console.WriteLine("Press any key to exit.");
            Console.ReadKey();
        }


        static void M(string s)
        {
            Console.WriteLine(s);
        }
    }
}

//无参
() => DoSomeThing() ;

//单参数
p => p.id > 0 ; //返回Bool

//多参数
( x , y ) => x * y ;

//带类型输入参数
( int x , int y ) => x * y;

var list1001=Studentlist.Where(t=>t.ClassCode==‘1001')；

var list1001=Studentlist.Where(t=>t.ClassCode==‘1001').OrderBy(t=>t.BirthDay)；

var list1001=Studentlist.Where(t=>t.ClassCode==‘1001'&&t.StudentName.StartWith（“李”）).OrderBy(t=>t.BirthDay)；

var result = studentList.Where(t => (t.ClassCode == "1001") && (scoreList.Exists(p => p.ScoreValue < 60 && p.StudentCode == t.StudentCode)));

var a = studentList.FirstOrDefault(t => t.StudentCode == "10012");//FirstOrDefault返回第一个符合条件的数据，不存在的时候返回Null。
var b = studentList.Count(t => t.StudentName == "李世民");//返回符合条件的实体个数
var c = studentList.FindAll(t => t.StudentName.Contains("中"));//查找所有名字中含有【中】的实体集合
var d = studentList.GroupBy(t => t.ClassCode);//对studentList按照ClassCode分组
var f = studentList.Max(t => t.BirthDay);//返回最大的出生日期。
var e = scoreList.Sum(t => t.ScoreValue);//对所有成绩求和
var g = scoreList.Average(t => t.ScoreValue);//对所有成绩求平均分
var h = studentList.Select(t => t.StudentName).Distinct();//获取所有的学生姓名，并去除重名