几种查询方法(lambda Linq Enumerable静态类方式)

using System;
using System.Collections.Generic;

namespace Linq
{
    public class Student
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }

    public class Data
    {
        public static List<Student> studentList = new List<Student>()
        {
            new Student()
            { Name="李四",
                Age=18
            },
            new Student()
            {
                Name="张三",
                Age=20
            }
        };

    }
}

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

namespace Linq
{
    class Program
    {
        static void Main(string[] args)
        {
            LinqTest lin = new LinqTest();
            lin.Show();
        }
    }
}

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

namespace Linq
{
    public class LinqTest
    {
        public  void Show()
        {
            List<Student> studentList = new List<Student>();//
            Console.WriteLine("-----------------foreach方式（1）---------");
          
            foreach (Student item in Data.studentList) ////Data.studentList是数据源
            {
                if (item.Age > 18)
                {
                    studentList.Add(item);//将数据源中满足要求的数据填充到指定容器中
                }
            }

           //studentList中以填充数据
            foreach (Student item in studentList)
            {
                Console.WriteLine("foreach方式:Name={0},Age={1}", item.Name, item.Age);
            }



            Console.WriteLine("-----------linq方式（2）-------------");
            var linq = from s in Data.studentList where s.Age > 18 select s;
            foreach (var item in linq)
            {
                Console.WriteLine("linq方式:Name={0},Age={1}", item.Name, item.Age);
            }



            Console.WriteLine("-----------lambda方式（3）-------------");
       // var lambda = Data.studentList.Where(s => s.Age > 18); where可以自动推断类型   扩展方法
            var lambda = Data.studentList.Where<Student>(s => s.Age > 18);
            foreach (var item in lambda)
            {
                Console.WriteLine("lambda方式:Name={0},Age={1}", item.Name, item.Age);
            }


            Console.WriteLine("-------Enumerable静态类方式（4）-----------");
          var  enm= Enumerable.Where(Data.studentList, s => s.Age > 18);
            foreach (var item in enm)
            {
                Console.WriteLine("Enumerable静态类方式：Name={0},Age={1}", item.Name, item.Age);
            }
        }

    }
}

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

namespace Linq
{
    public class LinqTest
    {
        public  void Show()
        {
            Console.WriteLine("-----------lambda方式（3.1）where扩展-------------");
            var linqExtend = Data.studentList.WhereExtend(s => s.Age > 18); //where可以自动推断类型   扩展方法
          
            foreach (var item in linqExtend)
            {
                Console.WriteLine("lambda方式（3.1）where扩展:Name={0},Age={1}", item.Name, item.Age);
            }
        }
    }
    /// <summary>
    /// where的扩展方法
    /// </summary>
    public static class LinqExtend
    {
        public static IEnumerable<T> WhereExtend<T>(this IEnumerable<T> tList,Func<T,bool> func) where T : Student// func:用于测试每个元素是否满足条件的函数。
        {
            var Linq = from s in tList where func(s) select s;
            return Linq;
        }

    }
}