C# Linq基本常用用法

 

1.什么是Linq？

　　Lanaguage Interated Query（语言集成查询），Linq 是集成C# 和VB这些语言中用于提供数据查询能力的一个新特性。

　　这里只介绍两种基本常用用法。

　　学习方法参考示例代码

1） where  查询

 class Program
    {
        static void Main(string[] args)
        {
            int[] nums = new int[] { 10, 2, 3, 100, 1, 5, 17, 82, 22, 3 };
            var result = from m in nums where m >= 10 select m;
            foreach (var v in result)
            {
                Console.WriteLine("v:" + v + "  ");
            }
            Console.WriteLine("\n");

            //使用Lambda 表达式进行Linq查询
            var result2 = nums.Where(m => m >= 10);
            foreach (var v in result2)
            {
                Console.WriteLine("v2:" + v + "  ");
            }

            List<People> mans = new List<People>();
            mans.Add(new People { id = 10, sex = true, name = "小王", birthday = Convert.ToDateTime("1994-1-1") });
            mans.Add(new People { id = 11, sex = false, name = "小张", birthday = Convert.ToDateTime("1954-1-1") });
            mans.Add(new People { id = 12, sex = true, name = "小明", birthday = Convert.ToDateTime("1993-1-1") });
            mans.Add(new People { id = 13, sex = false, name = "小红", birthday = Convert.ToDateTime("1974-1-1") });

            var resultMan = from man in mans where man.id < 11 && man.sex select man;
            foreach (var v in resultMan)
            {
                Console.WriteLine("v:"+v.id + " name :"+v.name);
            }
            Console.Read();
        }
    }

    class People
    {
        public string name { get; set; }
        public int id { get; set; }
        public bool sex { get; set; }
        public DateTime birthday { get; set; }
        public int GetAge()
        {
            return DateTime.Now.Year - birthday.Year;
        }
    }

2) order 排序

descending 降序

ascending 升序

  List<int> numbers = new List<int>() { 10, 11, 1, 2, 3, 7, 6 };

            var resultNums = from m in numbers orderby m  select m;
            foreach (var v in resultNums)
            {
                Console.WriteLine("v num:"+v);
            }
            Console.WriteLine("\n");
            var resultNums2 = from m in numbers orderby m descending select m;
            foreach (var v in resultNums2)
            {
                Console.WriteLine("v2 num:" + v);
            }
            Console.WriteLine("\n");

            var resultNums3 = from m in numbers orderby m ascending select m;
            foreach (var v in resultNums3)
            {
                Console.WriteLine("v3 num:" + v);
            }

 

 

2.优点

 　　1.简单，容易上手，极大节省开发效率。

　　 2.很大程度上节省代码量。

建议：Unity开发的话，一般都不要去使用，会产生GC。

参考链接：http://www.cnblogs.com/jara/p/3472215.html  http://www.cnblogs.com/hgmyz/p/7068150.html