using System;

using System.Collections.Generic;

using System.Linq;

​

public class Student

{

    public string FirstName;

    public string LastName;

    public DateTime DOB;

    public int Age

    {

        get

        {

            return DateTime.Today.Year - DOB.Year;  

        }

    }

    public Student(string firstName, string lastName, DateTime dob)

    {

        FirstName = firstName;

        LastName = lastName;

        DOB = dob;

    }

    public override String ToString()

    {

        return this.FirstName + " " + this.LastName;

    }   

​

    public static bool FirstNameExists(List<Student> students, String firstName)

    {

        var compareName = firstName.ToLower();

        foreach (Student st in students)

        {

            if (st.FirstName.ToLower().Contains(compareName)) return true;

        }

        return false;

    }

}

​

​

public class Program

{

    public static void Main()

    {

        var students = GetSampleStudentList();

        var orderedStudents = students.OrderBy(s=> s.DOB);

        foreach (Student st in orderedStudents)

        {

            Console.WriteLine(st + " Idade:" + st.Age);

        }

        Console.WriteLine(Student.FirstNameExists(students, "john"));

    }

​

    private static List<Student> GetSampleStudentList()

    {

        List<Student> students = new List<Student>();

        students.Add(new Student("John", "Smith", new DateTime(1978, 4, 16)));

        students.Add(new Student("John", "Rambo", new DateTime(1977, 3, 16)));

        students.Add(new Student("Jack", "Johnson", new DateTime(1981, 12, 13)));

        students.Add(new Student("John", "Jackson", new DateTime(1980, 1, 1)));

        students.Add(new Student("David", "Carson", new DateTime(1993, 5, 6)));

        students.Add(new Student("Steve", "Stephenson", new DateTime(1979, 7, 8)));

        return students;

    }

}