using System;

using System.Collections.Generic;

using System.Collections;

using System.Linq;

public class Program

{

    public static void Main()

    {

        IList mixedList = new ArrayList();

        mixedList.Add(0);

        mixedList.Add("One");

        mixedList.Add("Two");

        mixedList.Add(3);

        mixedList.Add(new Student() { StudentID = 1, StudentName = "Bill" });

        mixedList.Add(new Student() { StudentID = 2, StudentName = "Clinton" });

​

        var stringResult = from s in mixedList.OfType<string>()

                        select s;

​

        var intResult = from s in mixedList.OfType<int>()

                select s;

        var objStudent = from s in mixedList.OfType<Student>()

                select s;

        foreach(int k in intResult)

            Console.WriteLine(k);

        foreach(var k in stringResult)

            Console.WriteLine(k);

        foreach(var k in objStudent)

            Console.WriteLine(k.StudentID + " - " + k.StudentName);

    }

}

​

public class Student{

    public int StudentID{get;set;}

    public string StudentName{get;set;}

}