Linq学习笔记(1.7)——First、ElementAt、Any、all

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First()选择查询结果的第一个元素 Response.Write("<hr>用First()选择查询结果的第一个元素<br>"); Student student = (from s in GetStudents() where s.Language == "Chinese" select s) .First(); Response.Write(string.Format("<div class='result'>{0},{1},{2}</div>", student.Name, student.Age, student.Language)); //用First()的Lambda表达式选择查询结果的第一个元素 Response.Write("<hr>用First()的Lambda表达式选择查询结果的第一个元素<br>"); Student student2 = GetStudents().First(s => s.Age < 20); Response.Write(string.Format("<div class='result'>{0},{1},{2}</div>", student2.Name, student2.Age, student2.Language)); //用ElementAt()选择查询结果中指定位置的元素 Response.Write("<hr>用ElementAt()选择查询结果中指定位置的元素<br>"); Student student3 = GetStudents().ElementAt(3); Response.Write(string.Format("<div class='result'>{0},{1},{2}</div>", student3.Name, student3.Age, student3.Language)); //用Any判断查询结果中是否有元素满足条件 Response.Write("<hr>用Any判断查询结果中是否有元素满足条件<br>"); bool ifany = GetStudents().Any(s=>s.Age>20); Response.Write(ifany.ToString()); #endregion //用all()判断查询结果是否所有元素都满足条件 Response.Write("<hr>用all()判断查询结果是否所有元素都满足条件<br>"); bool ifall = GetStudents().All(s => s.Age > 20); Response.Write(ifall.ToString()); #endregion } //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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转自：http://www.cnblogs.com/young18/archive/2007/06/05/772810.html