C# List的使用

最新推荐文章于 2024-03-08 08:11:26 发布

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最新推荐文章于 2024-03-08 08:11:26 发布

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CC 4.0 BY-SA版权

文章标签：数据库

原文链接：http://www.cnblogs.com/peterYong/p/10881979.html

本文介绍C#中List的基本操作，包括排序、合并及数据处理，并演示了LINQ的强大功能，如条件筛选、排序及数据聚合，适用于C#初学者及进阶开发者。

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一、List排序

　　采用自定义Sort比较器和Linq

class Persion
    {
        public string name;
        public int age;
}
//自定义Sort方法
private static void sortListClass()
        {
            Persion p1 = new Persion() { name = "huyong", age = 27 };
            Persion p2 = new Persion() { name = "tansha", age = 25 };
            List<Persion> listPersion = new List<Persion>();
            listPersion.Add(p1);
            listPersion.Add(p2);
            listPersion.Sort(sortage);
            foreach (var item in listPersion)
            {
                Console.WriteLine(item.name + ":" + item.age);
            }
        }
        static int sortage(Persion x, Persion y)
        {
            if (x.age < y.age) return -1;                //按age从大到小 降序排列
            else if (x.age == y.age) return 0;
            else return 1;
        }
//linq方法
 private static void sortLinq()
        {
            Persion p1 = new Persion() { name = "huyong", age = 27 };
            Persion p2 = new Persion() { name = "tansha", age = 25 };
            Persion p3 = new Persion() { name = "tansha", age = 27 };
            List<Persion> listPersion = new List<Persion>();
            listPersion.Add(p1);
            listPersion.Add(p2);
            listPersion.Add(p3);

 var lList = from t in listPersion where (t.age == 27) orderby t.name ascending select t;
            foreach (var item in lList)
            {
                Console.WriteLine(item.name + ":" + item.age);
            }
        }

View Code

二、用Linq将两个list合并为一个list

  //linq合并两个list,根据某一相同字段
private static void mergeList()
        {
            Persion p1 = new Persion() { name = "hy", province = "jx" };
            Persion p2 = new Persion() { name = "tansha", province = "hn" };
            Persion p3 = new Persion() { name = "ht", province = "gd" };
            List<Persion> listPersion = new List<Persion>();
            listPersion.Add(p1);
            listPersion.Add(p2);
            listPersion.Add(p3);

            Persion p11 = new Persion() { name = "hy", age = 23, sex = "男" };
            Persion p21 = new Persion() { name = "tansha", age = 12, sex = "女" };
            Persion p31 = new Persion() { name = "ht", age = 7, sex = "男" };
            List<Persion> listPersion2 = new List<Persion>();
            listPersion2.Add(p11);
            listPersion2.Add(p21);
            listPersion2.Add(p31);

            //linq合并两个list,根据某一相同字段
            var list = from pp1 in listPersion
                       join pp2 in listPersion2 on pp1.name equals pp2.name
                       select new Persion
                       {
                           name = pp1.name,
                           province = pp1.province,
                           age = pp2.age,
                           sex = pp2.sex
                       };
            foreach (var item in list)
            {
                Console.WriteLine(item.name + ":" + item.age + ":" + item.sex + ":" + item.province);
            }
        }