Linq学习笔记(1.5)——group、Distinct、Union、Concat、Intersect、Except

sing#region using

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;

#endregion

public partial class _Default : System.Web.UI.Page 

{

    protected void Page_Load(object sender, EventArgs e)

    

{

        用group将集合体分组#region 用group将集合体分组

        Response.Write("<hr>用group将集合体分组：<br>");

        List<Student> StudentList = GetStudents();

        var students1 = from student in StudentList

                        group student by student.Language into studentsgroup

                        select new 

{Lang=studentsgroup.Key,member=studentsgroup};

        foreach (var g in students1)

        

{

            Response.Write(string.Format("<div class='result'>Language:{0}</div>",g.Lang));

            foreach (var student in g.member)

            

{

                Response.Write(string.Format("<div class='result'>——{0}</div>", student.Name));

            }

        }

        #endregion 

        用Distinct将过滤相同项#region 用Distinct将过滤相同项

        Response.Write("<hr>用Distinct将过滤相同项：<br>");

        var Languages = (from student in StudentList

                         select student.Language)

                        .Distinct();

        foreach (var l in Languages)

        

{

            Response.Write(string.Format("<span class='result'>{0}</span>", l));

        }

        #endregion

        用Union连接不同集合体#region 用Union连接不同集合体

        Response.Write("<hr>用Union连接不同集合体：<br>");

        string[] stringArray = 

{ "Csharp", "Javascript"};

        var Languages2 = (from student in StudentList

                          select student.Language)

                         .Union(stringArray);

        //Union会自动过滤各集合体中的相同项，无需Distinct

        foreach (var l in Languages2)

        

{

            Response.Write(string.Format("<span class='result'>{0}</span>", l));

        }

        #endregion

        用Concat连接不同集合体#region 用Concat连接不同集合体

        Response.Write("<hr>用Concat连接不同集合体：<br>");

        var Languages3 = (from student in StudentList

                          select student.Language)

                         .Concat(stringArray);

        //Concat不会自动过滤各集合体中的相同项

        foreach (var l in Languages3)

        

{

            Response.Write(string.Format("<span class='result'>{0}</span>", l));

        }

        #endregion

        用Intersect取不同集合体的相同项(交集)#region 用Intersect取不同集合体的相同项(交集)

        Response.Write("<hr>用Intersect取不同集合体的相同项(交集)：<br>");

        string[] Book1Array1 = 

{ "Csharp", "Javascript","FrameWork","Use Compute","WebDesign" };

        string[] Book1Array2 = 

{ "Chanese", "English", "Use Compute", "Business", "WebDesign" };

        var Books = Book1Array1.Intersect(Book1Array2);

        foreach (var book in Books)

        

{

            Response.Write(string.Format("<span class='result'>{0}</span>", book));

        }

        #endregion

        用Except从集合体中排出和另一个集合体相同的项#region 用Except从集合体中排出和另一个集合体相同的项

        Response.Write("<hr>用Except从集合体中排出和另一个集合体相同的项：<br>");

        var Books2 = Book1Array1.Except(Book1Array2);

        foreach (var book in Books2)

        

{

            Response.Write(string.Format("<span class='result'>{0}</span>", book));

        }

        #endregion

    }

   构造一个学生集合体#region 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;

    }

    #endregion

}

学生类#region 学生类

class Student

{

    public int Age 

{ get; set; }

    public string Name 

{ get; set; }

    public string Language 

{ get; set; }

}

#endregion
结果显示