Linq学习笔记(1.6)——ToArray、ToList、ToDictionary、OfType

最新推荐文章于 2025-06-28 09:02:55 发布

转载最新推荐文章于 2025-06-28 09:02:55 发布 · 1.1k 阅读

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#linq #class #dictionary #object #string #list

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本文通过示例展示了如何使用LINQ将查询结果转换为数组、List集合及Dictionary，并介绍了如何利用OfType方法过滤特定类型的对象。

using System; using System.Data; using System.Configuration; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Text; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using System.Collections.Generic; using System.Collections; public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { //用ToArray()将查询结果转化为数组 Response.Write("<hr>用ToArray将查询结果转化位数组 "); var students = from student in GetStudents() orderby student.Age select student.Name; var nameArray = students.ToArray(); foreach (var name in nameArray) { Response.Write(string.Format("{0}", name)); } //用ToList()将查询结果转化为List集合 Response.Write("<hr>用ToList()将查询结果转化为List集合 "); var students1 = from student in GetStudents() where student.Age>21 orderby student.Age select student.Name; var nameArray1 = students1.ToList(); nameArray1.Add("newlist"); foreach (var name in nameArray1) { Response.Write(string.Format("{0}", name)); } //用ToDictionary()将查询结果转化为Dictionary Response.Write("<hr>用ToDictionary()将查询结果转化为Dictionary "); var studentDict = GetStudents().ToDictionary(student => student.Name); var Y = studentDict["YOUNG"]; Response.Write(string.Format("YOUNG:{0},{1},{2}", Y.Name, Y.Age, Y.Language)); //用OfType过滤查询结果中的类型 Response.Write("<hr>用OfType过滤查询结果中的类型 "); object[] objects = { 1, "love",GetStudents()[1], 2.1, null, GetStudents()[3],"young"}; var students2 = objects.OfType<Student>(); foreach (var student in students2) { Response.Write(string.Format("{0}", student.Name)); } } //构造一个学生集合体 private List<Student> GetStudents() { List<Student> students = new List<Student> { new Student{ Name="YOUNG", Age=25, Language="Chinese"}, new Student{ Name="JESSIE", Age=21, Language="Scotland"}, new Student{ Name="KELLY", Age=18, Language="English"}, new Student{ Name="JUNE", Age=20, Language="English"}, new Student{ Name="ADRIAN", Age=22, Language="Italy"}, new Student{ Name="BRUCE", Age=17, Language="Scotland"}, new Student{ Name="BRANT", Age=30, Language="Germany"}, new Student{ Name="BEN", Age=25, Language="Chinese"} }; return students; } } //学生类 class Student { public int Age { get; set; } public string Name { get; set; } public string Language { get; set; } }

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