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Diffstat (limited to 'csharp.html.markdown')
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1 files changed, 370 insertions, 198 deletions
diff --git a/csharp.html.markdown b/csharp.html.markdown index 55de415d..dad0c26b 100644 --- a/csharp.html.markdown +++ b/csharp.html.markdown @@ -1,11 +1,11 @@ --- - language: c# contributors: - ["Irfan Charania", "https://github.com/irfancharania"] - ["Max Yankov", "https://github.com/golergka"] + - ["Melvyn Laïly", "http://x2a.yt"] + - ["Shaun McCarthy", "http://www.shaunmccarthy.com"] filename: LearnCSharp.cs - --- C# is an elegant and type-safe object-oriented language that enables developers to build a variety of secure and robust applications that run on the .NET Framework. @@ -24,7 +24,12 @@ Multi-line comments look like this // Specify namespaces application will be using using System; using System.Collections.Generic; - +using System.Data.Entity; +using System.Dynamic; +using System.Linq; +using System.Linq.Expressions; +using System.Net; +using System.Threading.Tasks; // defines scope to organize code into "packages" namespace Learning @@ -33,8 +38,8 @@ namespace Learning // you're allowed to do otherwise, but shouldn't for sanity. public class LearnCSharp { - // A console application must have a main method as an entry point - public static void Main(string[] args) + // 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"); @@ -47,7 +52,6 @@ namespace Learning Console.Write("Hello "); Console.Write("World"); - /////////////////////////////////////////////////// // Types & Variables // @@ -62,123 +66,83 @@ namespace Learning // (0 <= byte <= 255) byte fooByte = 100; - // Short - Signed 16-bit integer - // (-32,768 <= short <= 32,767) + // Short - 16-bit integer + // Signed - (-32,768 <= short <= 32,767) + // Unsigned - (0 <= ushort <= 65,535) short fooShort = 10000; - - // Ushort - Unsigned 16-bit integer - // (0 <= ushort <= 65,535) ushort fooUshort = 10000; - // Integer - Signed 32-bit integer - // (-2,147,483,648 <= int <= 2,147,483,647) - int fooInt = 1; + // 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) - // Uinteger - Unsigned 32-bit integer - // (0 <= uint <= 4,294,967,295) - uint fooUint = 1; - - // Long - Signed 64-bit integer - // (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807) - long fooLong = 100000L; + // 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 - // anything without is treated as int or uint depending on size. - // Ulong - Unsigned 64-bit integer - // (0 <= ulong <= 18,446,744,073,709,551,615) - ulong fooUlong = 100000L; + // 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 - // Precision: 7 digits - float fooFloat = 234.5f; - // f is used to denote that this variable value is of type float; - // otherwise it is treated as double. + float fooFloat = 234.5f; // Precision: 7 digits + // f is used to denote that this variable value is of type float - // Double - Double-precision 64-bit IEEE 754 Floating Point - // Precision: 15-16 digits - double fooDouble = 123.4; + // Decimal - a 128-bits data type, with more precision than other floating-point types, + // suited for financial and monetary calculations + decimal fooDecimal = 150.3m; - // Bool - true & false - bool fooBoolean = true; - bool barBoolean = false; + // Boolean - true & false + bool fooBoolean = true; // or false // Char - A single 16-bit Unicode character char fooChar = 'A'; - // Strings - string fooString = "My string is here!"; + // 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); - // formatting + // You can access each character of the string with an indexer: + char charFromString = fooString[1]; // 'y' + // 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); - Console.WriteLine(fooFormattedString); - // formatting dates + // Dates & Formatting DateTime fooDate = DateTime.Now; Console.WriteLine(fooDate.ToString("hh:mm, dd MMM yyyy")); - // \n is an escaped character that starts a new line - string barString = "Printing on a new line?\nNo Problem!"; - Console.WriteLine(barString); - - // it can be written prettier by using the @ symbol + // You can split a string over two lines with the @ symbol. To escape " use "" string bazString = @"Here's some stuff - on a new line!"; - Console.WriteLine(bazString); - - // quotes need to be escaped - // use \" normally - string quotedString = "some \"quoted\" stuff"; - Console.WriteLine(quotedString); - - // use "" when strings start with @ - string quotedString2 = @"some MORE ""quoted"" stuff"; - Console.WriteLine(quotedString2); +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 HOURS_I_WORK_PER_WEEK = 9001; - // Nullable types - // any type can be made nullable by suffixing a ? - // <type>? <var name> = <value> - int? nullable = null; - Console.WriteLine("Nullable variable: " + nullable); - - // In order to use nullable's value, you have to use Value property or to explicitly cast it - string? nullableString = "not null"; - Console.WriteLine("Nullable value is: " + nullableString.Value + " or: " + (string) nullableString ); - - // ?? is syntactic sugar for specifying default value - // in case variable is null - int notNullable = nullable ?? 0; - Console.WriteLine("Not nullable variable: " + notNullable); - - // Var - compiler will choose the most appropriate type based on value - var fooImplicit = true; - /////////////////////////////////////////////////// // Data Structures /////////////////////////////////////////////////// - Console.WriteLine("\n->Data Structures"); - // Arrays + // 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]; - string[] stringArray = new string[1]; - bool[] boolArray = new bool[100]; // 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 zero-indexed and mutable. + // Arrays are mutable. intArray[1] = 1; - Console.WriteLine("intArray @ 1: " + intArray[1]); // => 1 // Lists // Lists are used more frequently than arrays as they are more flexible @@ -186,28 +150,21 @@ namespace Learning // List<datatype> <var name> = new List<datatype>(); List<int> intList = new List<int>(); List<string> stringList = new List<string>(); - - // Another way to declare & initialize a list - List<int> z = new List<int> { 9000, 1000, 1337 }; - - // Indexing a list - Accessing an element - // Lists are zero-indexed and mutable. - Console.WriteLine("z @ 0: " + z[2]); + List<int> z = new List<int> { 9000, 1000, 1337 }; // intialize + // 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 + // Dictionary (an implementation of a hash map) + // HashSet // Read-only Collections // Tuple (.Net 4+) - /////////////////////////////////////// // Operators /////////////////////////////////////// @@ -216,10 +173,7 @@ namespace Learning int i1 = 1, i2 = 2; // Shorthand for multiple declarations // Arithmetic is straightforward - Console.WriteLine("1+2 = " + (i1 + i2)); // => 3 - Console.WriteLine("2-1 = " + (i2 - i1)); // => 1 - Console.WriteLine("2*1 = " + (i2 * i1)); // => 2 - Console.WriteLine("1/2 = " + (i1 / i2)); // => 0 (0.5 truncated down) + Console.WriteLine(i1 + i2 - i1 * 3 / 7); // // Modulo Console.WriteLine("11%3 = " + (11 % 3)); // => 2 @@ -237,7 +191,6 @@ namespace Learning ~ Unary bitwise complement << Signed left shift >> Signed right shift - >>> Unsigned right shift & Bitwise AND ^ Bitwise exclusive OR | Bitwise inclusive OR @@ -251,7 +204,6 @@ namespace Learning Console.WriteLine(i--); //i = 1. Post-Decrementation Console.WriteLine(--i); //i = 0. Pre-Decrementation - /////////////////////////////////////// // Control Structures /////////////////////////////////////// @@ -276,40 +228,39 @@ namespace Learning // A simple if/else can be written as follows // <condition> ? <true> : <false> string isTrue = (true) ? "True" : "False"; - Console.WriteLine("Ternary demo: " + isTrue); - // While loop int fooWhile = 0; while (fooWhile < 100) { - //Console.WriteLine(fooWhile); - //Increment the counter - //Iterated 99 times, fooWhile 0->99 + //Iterated 100 times, fooWhile 0->99 fooWhile++; } - Console.WriteLine("fooWhile Value: " + fooWhile); // Do While Loop int fooDoWhile = 0; do { - //Console.WriteLine(fooDoWhile); - //Increment the counter //Iterated 99 times, fooDoWhile 0->99 fooDoWhile++; } while (fooDoWhile < 100); - Console.WriteLine("fooDoWhile Value: " + fooDoWhile); - // For Loop - int fooFor; //for loop structure => for(<start_statement>; <conditional>; <step>) - for (fooFor = 0; fooFor < 10; fooFor++) + for (int fooFor = 0; fooFor < 10; fooFor++) { - //Console.WriteLine(fooFor); //Iterated 10 times, fooFor 0->9 } - Console.WriteLine("fooFor Value: " + fooFor); + + // 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. @@ -329,15 +280,21 @@ namespace Learning case 3: monthString = "March"; 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; } - Console.WriteLine("Switch Case Result: " + monthString); - /////////////////////////////////////// - // Converting Data Types And Typcasting + // Converting Data Types And Typecasting /////////////////////////////////////// // Converting data @@ -349,49 +306,231 @@ namespace Learning // try parse will default to type default on failure // in this case: 0 int tryInt; - int.TryParse("123", out tryInt); + if (int.TryParse("123", out tryInt)) // Funciton 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(); + } - /////////////////////////////////////// - // Classes And Functions - /////////////////////////////////////// - - Console.WriteLine("\n->Classes & Functions"); - - // (definition of the Bicycle class follows) + /////////////////////////////////////// + // 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.setCadence(100); + 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.ToString()); - - // Instantiate another new Bicycle - Bicycle octo = new Bicycle(5, 10); - Console.WriteLine("octo info: " + octo.ToString()); + Console.WriteLine("trek info: " + trek.Info()); // Instantiate a new Penny Farthing PennyFarthing funbike = new PennyFarthing(1, 10); - Console.WriteLine("funbike info: " + funbike.ToString()); + 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 + public static void MethodSignature(string maxCount) + { + } + + // 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()); + } + + public static void OtherInterestingFeatures() + { + // OPTIONAL PARAMETERS + MethodSignatures(3, 1, 3, "Some", "Extra", "Strings"); + MethodSignatures(3, another: 3); // explicity set a parameter, skipping optional ones + + // 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 + + // 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 + + // PARALLEL FRAMEWORK + // http://blogs.msdn.com/b/csharpfaq/archive/2010/06/01/parallel-programming-in-net-framework-4-getting-started.aspx + var websites = new string[] { + "http://www.google.com", "http://www.reddit.com", + "http://www.shaunmccarthy.com" + }; + var responses = new Dictionary<string, string>(); + + // Will spin up separate threads for each request, and join on them + // before going to the next step! + Parallel.ForEach(websites, + new ParallelOptions() {MaxDegreeOfParallelism = 3}, // max of 3 threads + website => + { + // Do something that takes a long time on the file + using (var r = WebRequest.Create(new Uri(website)).GetResponse()) + { + responses[website] = r.ContentType; + } + }); + + // This won't happen till after all requests have been completed + foreach (var key in responses.Keys) + Console.WriteLine("{0}:{1}", key, responses[key]); + + // 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 - combines 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 BikeRespository(); + + // execution is delayed, which is great when querying a database + var fitler = db.Bikes.Where(b => b.HasTassles); // no query run + if (42 > 6) // You can keep adding filters, even conditionally - great for "advanced search" functionality + fitler = fitler.Where(b => b.IsBroken); // no query run + + var query = fitler + .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 are 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 FUNCTIONS + public static void Print(this object obj) + { + Console.WriteLine(obj.ToString()); + } + } // Class Declaration Syntax: - // <public/private/protected> class <class name>{ + // <public/private/protected/internal> class <class name>{ // //data fields, constructors, functions all inside. // //functions are called as methods in Java. // } @@ -399,61 +538,88 @@ namespace Learning public class Bicycle { // Bicycle's Fields/Variables - public int cadence; // Public: Can be accessed from anywhere - private int _speed; // Private: Only accessible from within the class - protected int gear; // Protected: Accessible from the class and subclasses - internal int wheels; // Internal: Accessible from within the assembly - string name; // Everything is private by default: Only accessible from within this class + 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 proprety + { + _cadence = value; // Value is the value passed in to 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 privatee + public string Name { get; set; } // Enum is a value type that consists of a set of named constants - public enum Brand + // 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, + Electra = 42, //you can explicitly set a value to a name Gitane } // 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 Brand brand; // After declaing an enum type, we can declare the field of this type + public BikeBrand Brand; // After declaring an enum type, we can declare the field of this type // Static members belong to the type itself rather then specific object. - static public int bicyclesCreated = 0; // You can access them without a reference to any object: // Console.WriteLine("Bicycles created: " + Bicycle.bicyclesCreated); + static public int BicyclesCreated = 0; // 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 + readonly bool _hasCardsInSpokes = false; // read-only private // Constructors are a way of creating classes // This is a default constructor - private Bicycle() + public Bicycle() { - gear = 1; - cadence = 50; + this.Gear = 1; // you can access mmebers of the object with the keyword this + Cadence = 50; // but you don't always need it _speed = 5; - name = "Bontrager"; - brand = Brand.AIST; - bicyclesCreated++; + 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, Brand brand) + string name, bool hasCardsInSpokes, BikeBrand brand) + : base() // calls base first { - this.gear = startGear; // "this" keyword denotes the current object - this.cadence = startCadence; - this._speed = startSpeed; - this.name = name; // it can be useful when there's a name conflict - this.hasCardsInSpokes = hasCardsInSpokes; - this.brand = brand; + Gear = startGear; + Cadence = startCadence; + _speed = startSpeed; + Name = name; + _hasCardsInSpokes = hasCardsInSpokes; + Brand = brand; } // Constructors can be chained - public Bicycle(int startCadence, int startSpeed, Brand brand) : - this(startCadence, startSpeed, 0, "big wheels", true) + public Bicycle(int startCadence, int startSpeed, BikeBrand brand) : + this(startCadence, startSpeed, 0, "big wheels", true, brand) { } @@ -461,28 +627,10 @@ namespace Learning // <public/private/protected> <return type> <function name>(<args>) // classes can implement getters and setters for their fields - // or they can implement properties - - // Method declaration syntax: - // <scope> <return type> <method name>(<args>) - public int GetCadence() - { - return cadence; - } - - // void methods require no return statement - public void SetCadence(int newValue) - { - cadence = newValue; - } + // or they can implement properties (this is the preferred way in C#) - // virtual keyword indicates this method can be overridden - public virtual void SetGear(int newValue) - { - gear = newValue; - } - - // Method parameters can have defaut values. In this case, methods can be called with these parameters omitted + // 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; @@ -503,6 +651,12 @@ namespace Learning 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 { @@ -513,13 +667,13 @@ namespace Learning } //Method to display the attribute values of this Object. - public override string ToString() + public virtual string Info() { - return "gear: " + gear + - " cadence: " + cadence + - " speed: " + _speed + - " name: " + name + - " cards in spokes: " + (hasCardsInSpokes ? "yes" : "no") + + return "Gear: " + Gear + + " Cadence: " + Cadence + + " Speed: " + _speed + + " Name: " + Name + + " Cards in Spokes: " + (_hasCardsInSpokes ? "yes" : "no") + "\n------------------------------\n" ; } @@ -527,10 +681,11 @@ namespace Learning // Methods can also be static. It can be useful for helper methods public static bool DidWeCreateEnoughBycles() { - // Within a static method, we only can reference static class memebers - return bicyclesCreated > 9000; + // 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 @@ -541,20 +696,27 @@ namespace Learning // calling parent constructor public PennyFarthing(int startCadence, int startSpeed) : - base(startCadence, startSpeed, 0, "PennyFarthing", true) + base(startCadence, startSpeed, 0, "PennyFarthing", true, BikeBrand.Electra) { } - public override void SetGear(int gear) + protected override int Gear { - gear = 0; + get + { + return 0; + } + set + { + throw new ArgumentException("You can't change gears on a PennyFarthing"); + } } - public override string ToString() + public override string Info() { string result = "PennyFarthing bicycle "; result += base.ToString(); // Calling the base version of the method - return reuslt; + return result; } } @@ -566,7 +728,7 @@ namespace Learning interface IBreakable { - bool Broken { get; } // interfaces can contain properties as well as methods, fields & events + bool Broken { get; } // interfaces can contain properties as well as methods & events } // Class can inherit only one other class, but can implement any amount of interfaces @@ -579,7 +741,7 @@ namespace Learning damage += meters; } - public void Broken + public bool Broken { get { @@ -587,24 +749,34 @@ namespace Learning } } } -} // End Namespace + /// <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 BikeRespository : DbSet + { + public BikeRespository() + : base() + { + } + + public DbSet<Bicycle> Bikes { get; set; } + } +} // End Namespace ``` ## Topics Not Covered * Flags * Attributes - * Generics (T), Delegates, Func, Actions, lambda expressions * Static properties * Exceptions, Abstraction - * LINQ * ASP.NET (Web Forms/MVC/WebMatrix) * Winforms * Windows Presentation Foundation (WPF) - - ## Further Reading * [DotNetPerls](http://www.dotnetperls.com) |