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Select allows you to apply a transformation to every element in any data structure implementing IEnumerable. Getting the first character of each string in the following list: List<String> trees = new List<String>{ "Oak", "Birch", "Beech", "Elm", ...

Many LINQ functions both operate on an IEnumerable<TSource> and also return an IEnumerable<TResult>. The type parameters TSource and TResult may or may not refer to the same type, depending on the method in question and any functions passed to it. A few examples of this are public stat...

using System.Speech.Recognition; // ... SpeechRecognitionEngine recognitionEngine = new SpeechRecognitionEngine(); recognitionEngine.LoadGrammar(new DictationGrammar()); recognitionEngine.SpeechRecognized += delegate(object sender, SpeechRecognizedEventArgs e) { Console.WriteLine(&quot...

SpeechRecognitionEngine recognitionEngine = new SpeechRecognitionEngine(); GrammarBuilder builder = new GrammarBuilder(); builder.Append(new Choices("I am", "You are", "He is", "She is", "We are", "They are")); builder.Append(new Choices...

Install the NuGet package System.Reactive, then add this using statement to access the Rx extension methods: using System.Reactive.Linq;

emails.Where(email => email.From == "John")

emails.Select(email => email.Body)

Subscription returns an IDisposable: IDisposable subscription = emails.Subscribe(email => Console.WriteLine("Email from {0} to {1}", email.From, email.To)); When you are ready to unsubscribe, simply dispose the subscription: subscription.Dispose();

emails.Subscribe(email => Console.WriteLine("Email from {0} to {1}", email.From, email.To), cancellationToken);

string helloWorld = "Hello World!"; string world = helloWorld.Substring(6); //world = "World!" string hello = helloWorld.Substring(0,5); // hello = "Hello" Substring returns the string up from a given index, or between two indexes (both inclusive).

String.Trim() string x = " Hello World! "; string y = x.Trim(); // "Hello World!" string q = "{(Hi!*"; string r = q.Trim( '(', '*', '{' ); // "Hi!" String.TrimStart() and String.TrimEnd() string q = "{(Hi*"; string r = q.TrimStart( '{...

Use the String.Format() method to replace one or more items in the string with the string representation of a specified object: String.Format("Hello {0} Foo {1}", "World", "Bar") //Hello World Foo Bar

The following is a bad idea because it would dispose the db variable before returning it. public IDBContext GetDBContext() { using (var db = new DBContext()) { return db; } } This can also create more subtle mistakes: public IEnumerable<Person> GetPeople(int age)...

All six methods return a single value of the sequence type, and can be called with or without a predicate. Depending on the number of elements that match the predicate or, if no predicate is supplied, the number of elements in the source sequence, they behave as follows: First() Returns the fir...

Event declaration: public event EventHandler<EventArgsT> EventName; Event handler declaration: public void HandlerName(object sender, EventArgsT args) { /* Handler logic */ } Subscribing to the event: Dynamically: EventName += HandlerName; Through the Designer: Click the Events...

Event declaration: public event EventHandler<EventArgsType> EventName; Event handler declaration using lambda operator => and subscribing to the event: EventName += (obj, eventArgs) => { /* Handler logic */ }; Event handler declaration using delegate anonymous method syntax: Eve...

Events can be of any delegate type, not just EventHandler and EventHandler<T>. For example: //Declaring an event public event Action<Param1Type, Param2Type, ...> EventName; This is used similarly to standard EventHandler events: //Adding a named event handler public void HandlerNa...

Given an async method like this: Task<string> GetNameAsync(CancellationToken cancellationToken) Wrap it as an IObservable<string> like this: Observable.FromAsync(cancellationToken => GetNameAsync(cancellationToken))

Given an IObservable<Offer> of offers from merchants to buy or sell some type of item at a fixed price, we can match pairs of buyers and sellers as follows: var sellers = offers.Where(offer => offer.IsSell).Select(offer => offer.Merchant); var buyers = offers.Where(offer => offer.Is...

using System.Linq.Expressions; // Manually build the expression tree for // the lambda expression num => num < 5. ParameterExpression numParam = Expression.Parameter(typeof(int), "num"); ConstantExpression five = Expression.Constant(5, typeof(int)); BinaryExpression numLessTh...