c# linq <未完>

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

namespace demo_linq_select
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] a = new int[] {1, 2, 3, 4, 5};
            //select 为必选关键字 为前面满足条件的选择输出 返回结果为返回IEnumerable<TSOURCE>泛型接口
            IEnumerable<int> result = from r in a where r < 3 select r;
            Console.WriteLine(result.ToList());
            foreach (var t in result)
            {
                Console.WriteLine(t);
            }
            //匿名对象
            var obj = new { name = "leo", sex = "male" };
            Console.WriteLine(obj.name);
            Console.WriteLine(obj.sex);
            //LINQ高级扩展方式
            var result1 = a.Where(t => t < 3).Select(r => r); //where参数FUNC<TSOURCE, TRESULT>委托， 这里Select不是必须，
            //使用select实现对查询结果进行过滤，转换为一个新的对象等
            foreach (var t in result1)
            {
                Console.WriteLine(t);
            }

            var result2 = a.First();
            Console.WriteLine(result2);
            //Skip 跳过指定数量的元素
            var result3 = a.Skip(2).Where(r => r >= 4);
            print<int>(result3);

            //联合查询
            var b = new int[] {3, 4, 5, 6};
            var result4 = from c in a from d in b where c == d select c + d;
            print<int>(result4);
            Console.ReadKey();

        }

        static void print<T>(IEnumerable<T> result)
        {
            foreach (var t in result)
            {
                Console.WriteLine(t);
            }
        }
    }
}