using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        // Student collection

        IList<Student> studentList = new List<Student>() { 

                new Student() { StudentID = 1, StudentName = "John", Age = 13, 

                              Dob = new DateTimeOffset(2009, 5, 1, 8, 6, 32,

                                 new TimeSpan(1, 0, 0))} ,

                new Student() { StudentID = 2, StudentName = "Moin",  Age = 21,

                              Dob = new DateTimeOffset(2008, 5, 1, 8, 6, 32,

                                 new TimeSpan(1, 0, 0))} ,

                new Student() { StudentID = 3, StudentName = "Bill",  Age = 18,

                              Dob = new DateTimeOffset(2009, 5, 1, 8, 6, 32,

                                 new TimeSpan(1, 0, 0))} ,

                new Student() { StudentID = 4, StudentName = "Ram" , Age = 20,

                              Dob = new DateTimeOffset(2008, 5, 1, 8, 6, 32,

                                 new TimeSpan(1, 0, 0))} ,

                new Student() { StudentID = 5, StudentName = "Ron" , Age = 15,

                              Dob = new DateTimeOffset(2008, 5, 1, 8, 6, 32,

                                 new TimeSpan(1, 0, 0))} 

            };

        // LINQ Query Syntax to find out teenager students

        //var teenAgerStudent = studentList.GroupBy(a=>a.Dob).Select(g=>g.OrderBy(a=>a.Age));

        var b = studentList.GroupBy(a=>a.Dob).

            Select(g=>g.OrderBy(a=>a.Age))

            .SelectMany(a=>a).ToList();

        Console.WriteLine("Date:" +"                   "+ "Age");

        foreach(var a in b){

            Console.WriteLine(a.Dob.Date+ "    " + a.Age);

        }

    }

}

​

public class Student{

​

    public int StudentID { get; set; }

    public string StudentName { get; set; }

    public int Age { get; set; }

    public DateTimeOffset Dob {get; set;}

}