// import common useful library references... often from .NET Framework, then your own classes; this must be at the top of the source file

using System;

using System.Collections;

using System.Collections.Generic;

using System.Collections.Specialized;

using System.Linq;

​

// Classes, the "object oriented" way of exposing related variables and functionality in your app

// Lets you build smart objects that other developers interact with

// Only exposes what you want exposed

​

// Helper function to print the list in a sorta pretty way.

void printList(List<Person> list)

{

    foreach (var person in list)

    {

        Console.WriteLine(person.FirstName);

    }

        Console.WriteLine();

}

​

class Person

{

    string _firstName; // has a default value of Empty String and is PRIVATE

    string _lastName;   

    string _phoneNumber;

​

    public Char MiddleInitial { get; set; } // note this *Property* is public

​

    public String FirstName // another public property, ENFORCING BUSINESS RULES

    {

        get {

            return _firstName;

        }

        set {

            _firstName = value.Trim(); // clean up values before we store them - this is a "business rule"

        }

    }

    public Person()

    {

        // Default constructor.

    }

    public Person(String f, String l, String p)

    {

        _firstName = f;

        _lastName = l;

        _phoneNumber = p;

    }

}

​

​

// Loops, LINQ and Classes

​

var people = new List<Person>();

people.Add(new Person("Auri", "Rahimzadeh", "317.490.4321"));

people.Add(new Person("Steve", "Wozniak", "408.555.1212"));

people.Add(new Person("Scott", "Jones", "317.911.1234"));

people.Add(new Person("Eli", "McCord", "317.713.0000"));

​

var p = people.LastOrDefault(l => l.FirstName.StartsWith("S"));

Console.WriteLine("\n" + (p == null ? "null" : p.FirstName)

                  + "\n");

​

// Method syntax.

​

var sortedList = people.Where(w => w.FirstName.StartsWith("S"));

sortedList = sortedList.OrderBy(o => o.FirstName);

​

// Query syntax.

var sortedList2 = from person in people

                  where person.FirstName.StartsWith("S")

                   orderby person.FirstName

                   select person;

​

// Mixing Method and Query syntax.

var sortedList3 = people.Where(w => w.FirstName.StartsWith("S"));

sortedList3 = from person in sortedList3 orderby person.FirstName select person;

​

// Damn, this is ugly.

var sortedList4 = 

    from person 

    in people.Where(w => w.FirstName.StartsWith("S"))

    orderby person.FirstName 

    select person;

​

// Method chaining syntax.

var sortedList5 = people

    .Where(w => w.FirstName.StartsWith("S"))

    .OrderBy(o => o.FirstName);

​

printList(sortedList5.ToList());

​

Console.WriteLine("The type of sortedList5 is" + sortedList5.ToString());

​

// First or default.

var example = sortedList5.FirstOrDefault(f => f.FirstName.Contains("S"));

Console.WriteLine(example == null ? "null" : example.FirstName);

​

// Single or default.

var example2 = sortedList5.SingleOrDefault(f => f.FirstName.Contains("S"));

Console.WriteLine(example2 == null ? "null" : example2.FirstName);

​