// Single-line comments start with //

/*

Multi-line comments look like this

*/

/// <summary>

/// This is an XML documentation comment which can be used to generate external

/// documentation or provide context help within an IDE

/// </summary>

/// <param name="firstParam">This is some parameter documentation for firstParam</param>

/// <returns>Information on the returned value of a function</returns>

//public void MethodOrClassOrOtherWithParsableHelp(string firstParam) {}

​

// Specify the namespaces this source code will be using

// The namespaces below are all part of the standard .NET Framework Class Library

using System;

using System.Collections.Generic;

using System.Dynamic;

using System.Linq;

using System.Net;

using System.Threading.Tasks;

using System.IO;

​

// C# 6, static usingSystem.Math;

​

// But this one is not:

ystem.Data.Entity;

// In order to be able to use it, you need to add a dll reference

// This can be done with the NuGet package manager: `Install-Package EntityFramework`

​

// Namespaces define scope to organize code into "packages" or "modules"

// Using this code from another source file: using Learning.CSharp;

namespace Learning.CSharp

{

    // Each .cs file should at least contain a class with the same name as the file.

    // You're allowed to do otherwise, but shouldn't for sanity.

    public class LearnCSharp

    {

        // BASIC SYNTAX - skip to INTERESTING FEATURES if you have used Java or C++ before

        public static void Syntax()

        {

            // Use Console.WriteLine to print lines

            Console.WriteLine("Hello World");

            Console.WriteLine(

                "Integer: " + 10 +

                " Double: " + 3.14 +

                " Boolean: " + true);

​

            // To print without a new line, use Console.Write

            Console.Write("Hello ");

            Console.Write("World");

​

            ///////////////////////////////////////////////////

            // Types & Variables

            //

            // Declare a variable using <type> <name>

            ///////////////////////////////////////////////////

​

            // Sbyte - Signed 8-bit integer

            // (-128 <= sbyte <= 127)

            sbyte fooSbyte = 100;

​

            // Byte - Unsigned 8-bit integer

            // (0 <= byte <= 255)

            byte fooByte = 100;

​

            // Short - 16-bit integer

            // Signed - (-32,768 <= short <= 32,767)

            // Unsigned - (0 <= ushort <= 65,535)

            short fooShort = 10000;

            ushort fooUshort = 10000;

​

            // Integer - 32-bit integer

            int fooInt = 1; // (-2,147,483,648 <= int <= 2,147,483,647)

            uint fooUint = 1; // (0 <= uint <= 4,294,967,295)

​

            // Long - 64-bit integer

            long fooLong = 100000L; // (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807)

            ulong fooUlong = 100000L; // (0 <= ulong <= 18,446,744,073,709,551,615)

            // Numbers default to being int or uint depending on size.

            // L is used to denote that this variable value is of type long or ulong

​

            // Double - Double-precision 64-bit IEEE 754 Floating Point

            double fooDouble = 123.4; // Precision: 15-16 digits

​

            // Float - Single-precision 32-bit IEEE 754 Floating Point

            float fooFloat = 234.5f; // Precision: 7 digits

            // f is used to denote that this variable value is of type float

​

            // Decimal - a 128-bits data type, with more precision than other floating-point types,

            // suited for financial and monetary calculations

            decimal fooDecimal = 150.3m;

​

            // Boolean - true & false

            bool fooBoolean = true; // or false

​

            // Char - A single 16-bit Unicode character

            char fooChar = 'A';

​

            // Strings -- unlike the previous base types which are all value types,

            // a string is a reference type. That is, you can set it to null

            string fooString = "\"escape\" quotes and add \n (new lines) and \t (tabs)";

            Console.WriteLine(fooString);

​

            // You can access each character of the string with an indexer:

            char charFromString = fooString[1]; // => 'e'

            // Strings are immutable: you can't do fooString[1] = 'X';

​

            // Compare strings with current culture, ignoring case

            string.Compare(fooString, "x", StringComparison.CurrentCultureIgnoreCase);

​

            // Formatting, based on sprintf

            string fooFs = string.Format("Check Check, {0} {1}, {0} {1:0.0}", 1, 2);

​

            // Dates & Formatting

            DateTime fooDate = DateTime.Now;

            Console.WriteLine(fooDate.ToString("hh:mm, dd MMM yyyy"));

​

            // Verbatim String

            // You can use the @ symbol before a string literal to escape all characters in the string

            string path = "C:\\Users\\User\\Desktop";

            string verbatimPath = @"C:\Users\User\Desktop";

            Console.WriteLine(path == verbatimPath);  // => true

​

            // You can split a string over two lines with the @ symbol. To escape " use ""

            string bazString = @"Here's some stuff

on a new line! ""Wow!"", the masses cried";

​

            // Use const or read-only to make a variable immutable

            // const values are calculated at compile time

            const int HoursWorkPerWeek = 9001;

​

            ///////////////////////////////////////////////////

            // Data Structures

            ///////////////////////////////////////////////////

​

            // Arrays - zero indexed

            // The array size must be decided upon declaration

            // The format for declaring an array is follows:

            // <datatype>[] <var name> = new <datatype>[<array size>];

            int[] intArray = new int[10];

​

            // Another way to declare & initialize an array

            int[] y = { 9000, 1000, 1337 };

​

            // Indexing an array - Accessing an element

            Console.WriteLine("intArray @ 0: " + intArray[0]);

            // Arrays are mutable.

            intArray[1] = 1;

​

            // Lists

            // Lists are used more frequently than arrays as they are more flexible

            // The format for declaring a list is follows:

            // List<datatype> <var name> = new List<datatype>();

            List<int> intList = new List<int>();

            List<string> stringList = new List<string>();

            List<int> z = new List<int> { 9000, 1000, 1337 }; // initialize

            // The <> are for generics - Check out the cool stuff section

​

            // Lists don't default to a value;

            // A value must be added before accessing the index

            intList.Add(1);

            Console.WriteLine("intList @ 0: " + intList[0]);

​

            // Others data structures to check out:

            // Stack/Queue

            // Dictionary (an implementation of a hash map)

            // HashSet

            // Read-only Collections

            // Tuple (.Net 4+)

​

            ///////////////////////////////////////

            // Operators

            ///////////////////////////////////////

            Console.WriteLine("\n->Operators");

​

            int i1 = 1, i2 = 2; // Shorthand for multiple declarations

​

            // Arithmetic is straightforward

            Console.WriteLine(i1 + i2 - i1 * 3 / 7); // => 3

​

            // Modulo

            Console.WriteLine("11%3 = " + (11 % 3)); // => 2

​

            // Comparison operators

            Console.WriteLine("3 == 2? " + (3 == 2)); // => false

            Console.WriteLine("3 != 2? " + (3 != 2)); // => true

            Console.WriteLine("3 > 2? " + (3 > 2)); // => true

            Console.WriteLine("3 < 2? " + (3 < 2)); // => false

            Console.WriteLine("2 <= 2? " + (2 <= 2)); // => true

            Console.WriteLine("2 >= 2? " + (2 >= 2)); // => true

​

            // Bitwise operators!

            /*

            ~       Unary bitwise complement

            <<      Signed left shift

            >>      Signed right shift

            &       Bitwise AND

            ^       Bitwise exclusive OR

            |       Bitwise inclusive OR

            */

​

            // Incrementations

            int i = 0;

            Console.WriteLine("\n->Inc/Dec-rementation");

            Console.WriteLine(i++); //Prints "0", i = 1. Post-Incrementation

            Console.WriteLine(++i); //Prints "2", i = 2. Pre-Incrementation

            Console.WriteLine(i--); //Prints "2", i = 1. Post-Decrementation

            Console.WriteLine(--i); //Prints "0", i = 0. Pre-Decrementation

​

            ///////////////////////////////////////

            // Control Structures

            ///////////////////////////////////////

            Console.WriteLine("\n->Control Structures");

​

            // If statements are c-like

            int j = 10;

            if (j == 10)

            {

                Console.WriteLine("I get printed");

            }

            else if (j > 10)

            {

                Console.WriteLine("I don't");

            }

            else

            {

                Console.WriteLine("I also don't");

            }

​

            // Ternary operators

            // A simple if/else can be written as follows

            // <condition> ? <true> : <false>

            int toCompare = 17;

            string isTrue = toCompare == 17 ? "True" : "False";

​

            // While loop

            int fooWhile = 0;

            while (fooWhile < 100)

            {

                //Iterated 100 times, fooWhile 0->99

                fooWhile++;

            }

​

            // Do While Loop

            int fooDoWhile = 0;

            do

            {

                // Start iteration 100 times, fooDoWhile 0->99

                if (false)

                    continue; // skip the current iteration

​

                fooDoWhile++;

​

                if (fooDoWhile == 50)

                    break; // breaks from the loop completely

​

            } while (fooDoWhile < 100);

​

            //for loop structure => for(<start_statement>; <conditional>; <step>)

            for (int fooFor = 0; fooFor < 10; fooFor++)

            {

                //Iterated 10 times, fooFor 0->9

            }

​

            // For Each Loop

            // foreach loop structure => foreach(<iteratorType> <iteratorName> in <enumerable>)

            // The foreach loop loops over any object implementing IEnumerable or IEnumerable<T>

            // All the collection types (Array, List, Dictionary...) in the .Net framework

            // implement one or both of these interfaces.

            // (The ToCharArray() could be removed, because a string also implements IEnumerable)

            foreach (char character in "Hello World".ToCharArray())

            {

                //Iterated over all the characters in the string

            }

​

            // Switch Case

            // A switch works with the byte, short, char, and int data types.

            // It also works with enumerated types (discussed in Enum Types),

            // the String class, and a few special classes that wrap

            // primitive types: Character, Byte, Short, and Integer.

            int month = 3;

            string monthString;

            switch (month)

            {

                case 1:

                    monthString = "Januari";

                    break;

                case 2:

                    monthString = "Februari";

                    break;

                case 3:

                    monthString = "Maart";

                    break;

                // You can assign more than one case to an action

                // But you can't add an action without a break before another case

                // (if you want to do this, you would have to explicitly add a goto case x

                case 6:

                case 7:

                case 8:

                    monthString = "Summer time!!";

                    break;

                default:

                    monthString = "Some other month";

                    break;

            }

​

            ///////////////////////////////////////

            // Converting Data Types And Typecasting

            ///////////////////////////////////////

​

            // Converting data

​

            // Convert String To Integer

            // this will throw a FormatException on failure

            int.Parse("123");//returns an integer version of "123"

​

            // try parse will default to type default on failure

            // in this case: 0

            int tryInt;

            if (int.TryParse("123", out tryInt)) // Function is boolean

                Console.WriteLine(tryInt);       // 123

​

            // Convert Integer To String

            // Convert class has a number of methods to facilitate conversions

            Convert.ToString(123);

            // or

            tryInt.ToString();

​

            // Casting

            // Cast decimal 15 to an int

            // and then implicitly cast to long

            long x = (int) 15M;

        }

​

        ///////////////////////////////////////

        // CLASSES - see definitions at end of file

        ///////////////////////////////////////

        public static void Classes()

        {

            // See Declaration of objects at end of file

​

            // Use new to instantiate a class

            Bicycle trek = new Bicycle();

​

            // Call object methods

            trek.SpeedUp(3); // You should always use setter and getter methods

            trek.Cadence = 100;

​

            // ToString is a convention to display the value of this Object.

            Console.WriteLine("trek info: " + trek.Info());

​

            // Instantiate a new Penny Farthing

            PennyFarthing funbike = new PennyFarthing(1, 10);

            Console.WriteLine("funbike info: " + funbike.Info());

​

            Console.Read();

        } // End main method

​

        // CONSOLE ENTRY A console application must have a main method as an entry point

        public static void Main(string[] args)

        {

            OtherInterestingFeatures();

        }

​

        //

        // INTERESTING FEATURES

        //

​

        // DEFAULT METHOD SIGNATURES

​

        public // Visibility

        static // Allows for direct call on class without object

        int // Return Type,

        MethodSignatures(

            int maxCount, // First variable, expects an int

            int count = 0, // will default the value to 0 if not passed in

            int another = 3,

            params string[] otherParams // captures all other parameters passed to method

        )

        {

            return -1;

        }

​

        // Methods can have the same name, as long as the signature is unique

        // A method that differs only in return type is not unique

        public static void MethodSignatures(

            ref int maxCount, // Pass by reference

            out int count)

        {

            //the argument passed in as 'count' will hold the value of 15 outside of this function

            count = 15; // out param must be assigned before control leaves the method

        }

​

        // GENERICS

        // The classes for TKey and TValue is specified by the user calling this function.

        // This method emulates the SetDefault of Python

        public static TValue SetDefault<TKey, TValue>(

            IDictionary<TKey, TValue> dictionary,

            TKey key,

            TValue defaultItem)

        {

            TValue result;

            if (!dictionary.TryGetValue(key, out result))

                return dictionary[key] = defaultItem;

            return result;

        }

​

        // You can narrow down the objects that are passed in

        public static void IterateAndPrint<T>(T toPrint) where T: IEnumerable<int>

        {

            // We can iterate, since T is a IEnumerable

            foreach (var item in toPrint)

                // Item is an int

                Console.WriteLine(item.ToString());

        }

​

        // YIELD

        // Usage of the "yield" keyword indicates that the method it appears in is an Iterator

        // (this means you can use it in a foreach loop)

        public static IEnumerable<int> YieldCounter(int limit = 10)

        {

            for (var i = 0; i < limit; i++)

                yield return i;

        }

​

        // which you would call like this :

        public static void PrintYieldCounterToConsole()

        {

            foreach (var counter in YieldCounter())

                Console.WriteLine(counter);

        }

​

        // you can use more than one "yield return" in a method

        public static IEnumerable<int> ManyYieldCounter()

        {

            yield return 0;

            yield return 1;

            yield return 2;

            yield return 3;

        }

​

        // you can also use "yield break" to stop the Iterator

        // this method would only return half of the values from 0 to limit.

        public static IEnumerable<int> YieldCounterWithBreak(int limit = 10)

        {

            for (var i = 0; i < limit; i++)

            {

                if (i > limit/2) yield break;

                yield return i;

            }

        }

​

        public static void OtherInterestingFeatures()

        {

            // OPTIONAL PARAMETERS

            MethodSignatures(3, 1, 3, "Some", "Extra", "Strings");

            MethodSignatures(3, another: 3); // explicitly set a parameter, skipping optional ones

​

            // BY REF AND OUT PARAMETERS

            int maxCount = 0, count; // ref params must have value

            MethodSignatures(ref maxCount, out count);

​

            // EXTENSION METHODS

            int i = 3;

            i.Print(); // Defined below

​

            // NULLABLE TYPES - great for database interaction / return values

            // any value type (i.e. not a class) can be made nullable by suffixing a ?

            // <type>? <var name> = <value>

            int? nullable = null; // short hand for Nullable<int>

            Console.WriteLine("Nullable variable: " + nullable);

            bool hasValue = nullable.HasValue; // true if not null

​

            // ?? is syntactic sugar for specifying default value (coalesce)

            // in case variable is null

            int notNullable = nullable ?? 0; // 0

​

            // ?. is an operator for null-propagation - a shorthand way of checking for null

            nullable?.Print(); // Use the Print() extension method if nullable isn't null

​

            // IMPLICITLY TYPED VARIABLES - you can let the compiler work out what the type is:

            var magic = "magic is a string, at compile time, so you still get type safety";

            // magic = 9; will not work as magic is a string, not an int

​

            // GENERICS

            //

            var phonebook = new Dictionary<string, string>() {

                {"Sarah", "212 555 5555"} // Add some entries to the phone book

            };

​

            // Calling SETDEFAULT defined as a generic above

            Console.WriteLine(SetDefault<string,string>(phonebook, "Shaun", "No Phone")); // No Phone

            // nb, you don't need to specify the TKey and TValue since they can be

            // derived implicitly

            Console.WriteLine(SetDefault(phonebook, "Sarah", "No Phone")); // 212 555 5555

​

            // LAMBDA EXPRESSIONS - allow you to write code in line

            Func<int, int> square = (x) => x * x; // Last T item is the return value

            Console.WriteLine(square(3)); // 9

​

            // ERROR HANDLING - coping with an uncertain world

            try

            {

                var funBike = PennyFarthing.CreateWithGears(6);

​

                // will no longer execute because CreateWithGears throws an exception

                string some = "";

                if (true) some = null;

                some.ToLower(); // throws a NullReferenceException

            }

            catch (NotSupportedException)

            {

                Console.WriteLine("Not so much fun now!");

            }

            catch (Exception ex) // catch all other exceptions

            {

                throw new ApplicationException("It hit the fan", ex);

                // throw; // A rethrow that preserves the callstack

            }

            // catch { } // catch-all without capturing the Exception

            finally

            {

                // executes after try or catch

            }

​

            // DISPOSABLE RESOURCES MANAGEMENT - let you handle unmanaged resources easily.

            // Most of objects that access unmanaged resources (file handle, device contexts, etc.)

            // implement the IDisposable interface. The using statement takes care of

            // cleaning those IDisposable objects for you.

            using (StreamWriter writer = new StreamWriter("log.txt"))

            {

                writer.WriteLine("Nothing suspicious here");

                // At the end of scope, resources will be released.

                // Even if an exception is thrown.

            }

​

            // PARALLEL FRAMEWORK

            // http://blogs.msdn.com/b/csharpfaq/archive/2010/06/01/parallel-programming-in-net-framework-4-getting-started.aspx

​

            var words = new List<string> {"dog", "cat", "horse", "pony"};

​

            Parallel.ForEach(words,

                new ParallelOptions() { MaxDegreeOfParallelism = 4 },

                word =>

                {

                    Console.WriteLine(word);

                }

            );

​

            //Running this will produce different outputs

            //since each thread finishes at different times.

            //Some example outputs are:

            //cat dog horse pony

            //dog horse pony cat

​

            // DYNAMIC OBJECTS (great for working with other languages)

            dynamic student = new ExpandoObject();

            student.FirstName = "First Name"; // No need to define class first!

​

            // You can even add methods (returns a string, and takes in a string)

            student.Introduce = new Func<string, string>(

                (introduceTo) => string.Format("Hey {0}, this is {1}", student.FirstName, introduceTo));

            Console.WriteLine(student.Introduce("Beth"));

​

            // IQUERYABLE<T> - almost all collections implement this, which gives you a lot of

            // very useful Map / Filter / Reduce style methods

            var bikes = new List<Bicycle>();

            bikes.Sort(); // Sorts the array

            bikes.Sort((b1, b2) => b1.Wheels.CompareTo(b2.Wheels)); // Sorts based on wheels

            var result = bikes

                .Where(b => b.Wheels > 3) // Filters - chainable (returns IQueryable of previous type)

                .Where(b => b.IsBroken && b.HasTassles)

                .Select(b => b.ToString()); // Map - we only this selects, so result is a IQueryable<string>

​

            var sum = bikes.Sum(b => b.Wheels); // Reduce - sums all the wheels in the collection

​

            // Create a list of IMPLICIT objects based on some parameters of the bike

            var bikeSummaries = bikes.Select(b=>new { Name = b.Name, IsAwesome = !b.IsBroken && b.HasTassles });

            // Hard to show here, but you get type ahead completion since the compiler can implicitly work

            // out the types above!

            foreach (var bikeSummary in bikeSummaries.Where(b => b.IsAwesome))

                Console.WriteLine(bikeSummary.Name);

​

            // ASPARALLEL

            // And this is where things get wicked - combine linq and parallel operations

            var threeWheelers = bikes.AsParallel().Where(b => b.Wheels == 3).Select(b => b.Name);

            // this will happen in parallel! Threads will automagically be spun up and the

            // results divvied amongst them! Amazing for large datasets when you have lots of

            // cores

​

            // LINQ - maps a store to IQueryable<T> objects, with delayed execution

            // e.g. LinqToSql - maps to a database, LinqToXml maps to an xml document

            var db = new BikeRepository();

​

            // execution is delayed, which is great when querying a database

            var filter = db.Bikes.Where(b => b.HasTassles); // no query run

            if (42 > 6) // You can keep adding filters, even conditionally - great for "advanced search" functionality

                filter = filter.Where(b => b.IsBroken); // no query run

​

            var query = filter

                .OrderBy(b => b.Wheels)

                .ThenBy(b => b.Name)

                .Select(b => b.Name); // still no query run

​

            // Now the query runs, but opens a reader, so only populates as you iterate through

            foreach (string bike in query)

                Console.WriteLine(result);

​

​

​

        }

​

    } // End LearnCSharp class

​

    // You can include other classes in a .cs file

​

    public static class Extensions

    {

        // EXTENSION METHODS

        public static void Print(this object obj)

        {

            Console.WriteLine(obj.ToString());

        }

    }

​

​

    // DELEGATES AND EVENTS

    public class DelegateTest

    {

        public static int count = 0;

        public static int Increment()

        {

            // increment count then return it

            return ++count;

        }

​

        // A delegate is a reference to a method

        // To reference the Increment method,

        // first declare a delegate with the same signature

        // ie. takes no arguments and returns an int

        public delegate int IncrementDelegate();

​

        // An event can also be used to trigger delegates

        // Create an event with the delegate type

        public static event IncrementDelegate MyEvent;

​

        static void Main(string[] args)

        {

            // Refer to the Increment method by instantiating the delegate

            // and passing the method itself in as an argument

            IncrementDelegate inc = new IncrementDelegate(Increment);

            Console.WriteLine(inc());  // => 1

​

            // Delegates can be composed with the + operator

            IncrementDelegate composedInc = inc;

            composedInc += inc;

            composedInc += inc;

​

            // composedInc will run Increment 3 times

            Console.WriteLine(composedInc());  // => 4

​

​

            // Subscribe to the event with the delegate

            MyEvent += new IncrementDelegate(Increment);

            MyEvent += new IncrementDelegate(Increment);

​

            // Trigger the event

            // ie. run all delegates subscribed to this event

            Console.WriteLine(MyEvent());  // => 6

        }

    }

​

​

    // Class Declaration Syntax:

    // <public/private/protected/internal> class <class name>{

    //    //data fields, constructors, functions all inside.

    //    //functions are called as methods in Java.

    // }

​

    public class Bicycle

    {

        // Bicycle's Fields/Variables

        public int Cadence // Public: Can be accessed from anywhere

        {

            get // get - define a method to retrieve the property

            {

                return _cadence;

            }

            set // set - define a method to set a property

            {

                _cadence = value; // Value is the value passed in to the setter

            }

        }

        private int _cadence;

​

        protected virtual int Gear // Protected: Accessible from the class and subclasses

        {

            get; // creates an auto property so you don't need a member field

            set;

        }

​

        internal int Wheels // Internal: Accessible from within the assembly

        {

            get;

            private set; // You can set modifiers on the get/set methods

        }

​

        int _speed; // Everything is private by default: Only accessible from within this class.

                    // can also use keyword private

        public string Name { get; set; }

​

        // Properties also have a special syntax for when you want a readonly property

        // that simply returns the result of an expression

        public string LongName => Name + " " + _speed + " speed"; 

​

        // Enum is a value type that consists of a set of named constants

        // It is really just mapping a name to a value (an int, unless specified otherwise).

        // The approved types for an enum are byte, sbyte, short, ushort, int, uint, long, or ulong.

        // An enum can't contain the same value twice.

        public enum BikeBrand

        {

            AIST,

            BMC,

            Electra = 42, //you can explicitly set a value to a name

            Gitane // 43

        }

        // We defined this type inside a Bicycle class, so it is a nested type

        // Code outside of this class should reference this type as Bicycle.Brand

​

        public BikeBrand Brand; // After declaring an enum type, we can declare the field of this type

​

        // Decorate an enum with the FlagsAttribute to indicate that multiple values can be switched on

        // Any class derived from Attribute can be used to decorate types, methods, parameters etc

        // Bitwise operators & and | can be used to perform and/or operations

​

        [Flags]

        public enum BikeAccessories

        {

            None = 0,

            Bell = 1,

            MudGuards = 2, // need to set the values manually!

            Racks = 4,

            Lights = 8,

            FullPackage = Bell | MudGuards | Racks | Lights

        }

​

        // Usage: aBike.Accessories.HasFlag(Bicycle.BikeAccessories.Bell)

        // Before .NET 4: (aBike.Accessories & Bicycle.BikeAccessories.Bell) == Bicycle.BikeAccessories.Bell

        public BikeAccessories Accessories { get; set; }

​

        // Static members belong to the type itself rather than specific object.

        // You can access them without a reference to any object:

        // Console.WriteLine("Bicycles created: " + Bicycle.bicyclesCreated);

        public static int BicyclesCreated { get; set; }

​

        // readonly values are set at run time

        // they can only be assigned upon declaration or in a constructor

        readonly bool _hasCardsInSpokes = false; // read-only private

​

        // Constructors are a way of creating classes

        // This is a default constructor

        public Bicycle()

        {

            this.Gear = 1; // you can access members of the object with the keyword this

            Cadence = 50;  // but you don't always need it

            _speed = 5;

            Name = "Bontrager";

            Brand = BikeBrand.AIST;

            BicyclesCreated++;

        }

​

        // This is a specified constructor (it contains arguments)

        public Bicycle(int startCadence, int startSpeed, int startGear,

                       string name, bool hasCardsInSpokes, BikeBrand brand)

            : base() // calls base first

        {

            Gear = startGear;

            Cadence = startCadence;

            _speed = startSpeed;

            Name = name;

            _hasCardsInSpokes = hasCardsInSpokes;

            Brand = brand;

        }

​

        // Constructors can be chained

        public Bicycle(int startCadence, int startSpeed, BikeBrand brand) :

            this(startCadence, startSpeed, 0, "big wheels", true, brand)

        {

        }

​

        // Function Syntax:

        // <public/private/protected> <return type> <function name>(<args>)

​

        // classes can implement getters and setters for their fields

        // or they can implement properties (this is the preferred way in C#)

​

        // Method parameters can have default values.

        // In this case, methods can be called with these parameters omitted

        public void SpeedUp(int increment = 1)

        {

            _speed += increment;

        }

​

        public void SlowDown(int decrement = 1)

        {

            _speed -= decrement;

        }

​

        // properties get/set values

        // when only data needs to be accessed, consider using properties.

        // properties may have either get or set, or both

        private bool _hasTassles; // private variable

        public bool HasTassles // public accessor

        {

            get { return _hasTassles; }

            set { _hasTassles = value; }

        }

​

        // You can also define an automatic property in one line

        // this syntax will create a backing field automatically.

        // You can set an access modifier on either the getter or the setter (or both)

        // to restrict its access:

        public bool IsBroken { get; private set; }

​

        // Properties can be auto-implemented

        public int FrameSize

        {

            get;

            // you are able to specify access modifiers for either get or set

            // this means only Bicycle class can call set on Framesize

            private set;

        }

​

        // It's also possible to define custom Indexers on objects.

        // All though this is not entirely useful in this example, you

        // could do bicycle[0] which returns "chris" to get the first passenger or

        // bicycle[1] = "lisa" to set the passenger. (of this apparent quattrocycle)

        private string[] passengers = { "chris", "phil", "darren", "regina" };

​

        public string this[int i]

        {

            get {

                return passengers[i];

            }

​

            set {

                passengers[i] = value;

            }

        }

​

        //Method to display the attribute values of this Object.

        public virtual string Info()

        {

            return "Gear: " + Gear +

                    " Cadence: " + Cadence +

                    " Speed: " + _speed +

                    " Name: " + Name +

                    " Cards in Spokes: " + (_hasCardsInSpokes ? "yes" : "no") +

                    "\n------------------------------\n"

                    ;

        }

​

        // Methods can also be static. It can be useful for helper methods

        public static bool DidWeCreateEnoughBicycles()

        {

            // Within a static method, we only can reference static class members

            return BicyclesCreated > 9000;

        } // If your class only needs static members, consider marking the class itself as static.

​

​

    } // end class Bicycle

​

    // PennyFarthing is a subclass of Bicycle

    class PennyFarthing : Bicycle

    {

        // (Penny Farthings are those bicycles with the big front wheel.

        // They have no gears.)

​

        // calling parent constructor

        public PennyFarthing(int startCadence, int startSpeed) :

            base(startCadence, startSpeed, 0, "PennyFarthing", true, BikeBrand.Electra)

        {

        }

​

        protected override int Gear

        {

            get

            {

                return 0;

            }

            set

            {

                throw new InvalidOperationException("You can't change gears on a PennyFarthing");

            }

        }

​

        public static PennyFarthing CreateWithGears(int gears)

        {

            var penny = new PennyFarthing(1, 1);

            penny.Gear = gears; // Oops, can't do this!

            return penny;

        }

​

        public override string Info()

        {

            string result = "PennyFarthing bicycle ";

            result += base.ToString(); // Calling the base version of the method

            return result;

        }

    }

​

    // Interfaces only contain signatures of the members, without the implementation.

    interface IJumpable

    {

        void Jump(int meters); // all interface members are implicitly public

    }

​

    interface IBreakable

    {

        bool Broken { get; } // interfaces can contain properties as well as methods & events

    }

​

    // Classes can inherit only one other class, but can implement any amount of interfaces,

    // however the base class name must be the first in the list and all interfaces follow

    class MountainBike : Bicycle, IJumpable, IBreakable

    {

        int damage = 0;

​

        public void Jump(int meters)

        {

            damage += meters;

        }

​

        public bool Broken

        {

            get

            {

                return damage > 100;

            }

        }

    }

​

    /// <summary>

    /// Used to connect to DB for LinqToSql example.

    /// EntityFramework Code First is awesome (similar to Ruby's ActiveRecord, but bidirectional)

    /// http://msdn.microsoft.com/en-us/data/jj193542.aspx

    /// </summary>

   /*  public class BikeRepository : DbContext

    {

        public BikeRepository()

            : base()

        {

        }

​

        public DbSet<Bicycle> Bikes { get; set; }

    }

*/

    // Classes can be split across multiple .cs files

    // A1.cs

    public partial class A

    {

        public static void A1()

        {

            Console.WriteLine("Method A1 in class A");

        }

    }

​

    // A2.cs

    public partial class A

    {

        public static void A2()

        {

            Console.WriteLine("Method A2 in class A");

        }

    }

​

    // Program using the partial class "A"

    public class Program

    {

        static void Main()

        {

            A.A1();

            A.A2();

        }

    }

​

    // String interpolation by prefixing the string with $

    // and wrapping the expression you want to interpolate with { braces }

    // You can also combine both interpolated and verbatim strings with $@

    public class Rectangle

    {

        public int Length { get; set; }

        public int Width { get; set; }

    }

​

    class Program2

    {

        static void Main(string[] args)

        {

            Rectangle rect = new Rectangle { Length = 5, Width = 3 };

           // Console.WriteLine($"The length is {rect.Length} and the width is {rect.Width}");

​

            string username = "User";

         //   Console.WriteLine($@"C:\Users\{username}\Desktop");

        }

    }

​

    // New C# 6 features

    class GlassBall : IJumpable, IBreakable

    {

        // Autoproperty initializers

        public int Damage { get; private set; } = 0;

​

        // Autoproperty initializers on getter-only properties

        public string Name { get; } = "Glass ball";

​

        // Getter-only autoproperty that is initialized in constructor

        public string GenieName { get; }

​

        public GlassBall(string genieName = null)

        {

            GenieName = genieName;

        }

​

        public void Jump(int meters)

        {

            if (meters < 0)

                // New nameof() expression; compiler will check that the identifier exists

                // nameof(x) == "x"

                // Prevents e.g. parameter names changing but not updated in error messages

                throw new ArgumentException("Cannot jump negative amount!", nameof(meters));

​

            Damage += meters;

        }

​

        // Expression-bodied properties ...

        public bool Broken

            => Damage > 100;

​

        // ... and methods

        public override string ToString()

            // Interpolated string

            => //$"{Name}. Damage taken: {Damage}";

​

        public string SummonGenie()

            // Null-conditional operators

            // x?.y will return null immediately if x is null; y is not evaluated

            => GenieName?.ToUpper();

    }

​

    static class MagicService

    {

        private static bool LogException(Exception ex)

        {

            /* log exception somewhere */

            return false;

        }

​

        public static bool CastSpell(string spell)

        {

            try

            {

                // Pretend we call API here

                throw new MagicServiceException("Spell failed", 42);

​

                // Spell succeeded

                return true;

            }

            // Only catch if Code is 42 i.e. spell failed

            catch(MagicServiceException ex) when (ex.Code == 42)

            {

                // Spell failed

                return false;

            }

            // Other exceptions, or MagicServiceException where Code is not 42 

            catch(Exception ex) when (LogException(ex))

            {

                // Execution never reaches this block

                // The stack is not unwound

            }

            return false;

            // Note that catching a MagicServiceException and rethrowing if Code

            // is not 42 or 117 is different, as then the final catch-all block

            // will not catch the rethrown exception

        }

    }