C# Linq

class Program
    {
        static void Main(string[] args)
        {
            {
                //普通查询
                foreach(var item  in StuList)
                {
                    if(item.Age>=20)
                    {
                        Console.WriteLine($"Id:{item.Id},姓名：{item.name},年龄：{item.Age}");
                    }
                }
            }
            {
                //扩展方法
                var list = StuList.Where(s=>s.Age <= 20);
                foreach(var item in list)
                {
                    Console.WriteLine($"Id:{item.Id},姓名：{item.name},年龄：{item.Age}");
                }
            }
            {
                //关键词方法
                var list = from s in StuList
                           where s.Age <= 20
                           select s;
                foreach (var item in list)
                {
                    Console.WriteLine($"Id:{item.Id},姓名：{item.name},年龄：{item.Age}");
                }
            }
        }
    }

Linq方法：

Where()

Count()

Select()