using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        /*

        TAccumulate Aggregate<TSource, TAccumulate>(TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> func);

        */

        // Student collection

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

        { 

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

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

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

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

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

        };

        string commaSeperatedStudentNames = studentList.Aggregate<Student, string>(

        "Student Names: ", // seed the value

        (str, s) => str += s.StudentName + ",");

        Console.WriteLine(commaSeperatedStudentNames);

        Console.WriteLine();

        int sumOfStudentsAge = studentList.Aggregate<Student, int>(0, 

                                                                  (age, s) => age += s.Age );

        Console.WriteLine(sumOfStudentsAge);

    }

}

​

public class Student

{

    public int StudentID { get; set; }

    public string StudentName { get; set; }

    public int Age { get; set; }

}