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C# List的使用

發(fā)布時間：2025/3/21 C# 20 豆豆

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一、List排序

　　采用自定義Sort比較器和Linq

class Persion{public string name;public int age; } //自定義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從大到小降序排列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將兩個list合并為一個list

//linq合并兩個list,根據(jù)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合并兩個list,根據(jù)某一相同字段var list = from pp1 in listPersionjoin pp2 in listPersion2 on pp1.name equals pp2.nameselect 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);}} View Code

三、對List里面的某個數(shù)據(jù)進行操作并保存

lists.Where(q =>q.SellChannelId == ((int)SellChannelType.PB).ToString()).ToList().ForEach(q => q.index = 10);

四、List<T>轉(zhuǎn)化為IQueryable<T>

　　不能直接轉(zhuǎn)換，

IQueryable在數(shù)據(jù)庫端中查詢，

IEnumerable在內(nèi)存上查詢。

List<T>支持后者?？梢杂?list.AsQueryable<T>轉(zhuǎn)換。

轉(zhuǎn)載于:https://www.cnblogs.com/peterYong/p/10881979.html

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