linq

#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)
    {
        #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 

        #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

        #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

        #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

        #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

        #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 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 学生类
class Student
{
    public int Age { get; set; }
    public string Name { get; set; }
    public string Language { get; set; }
}
#endregion