Tutorial by Examples: e

Enumerable.Select returns an output element for every input element. Whereas Enumerable.SelectMany produces a variable number of output elements for each input element. This means that the output sequence may contain more or fewer elements than were in the input sequence. Lambda expressions passe...

This method takes the first n elements from an enumerable. var numbers = new[] {1,2,3,4,5}; var threeFirstNumbers = numbers.Take(3); Console.WriteLine(string.Join(",", threeFirstNumbers.ToArray())); //1,2,3

var numbers = new[] {1,2,3,4,5}; var sameNumbers = new[] {1,2,3,4,5}; var sameNumbersInDifferentOrder = new[] {5,1,4,2,3}; var equalIfSameOrder = numbers.SequenceEqual(sameNumbers); Console.WriteLine(equalIfSameOrder); //True var equalIfDifferentOrder = numbers.SequenceEqual(sameNumbersInDi...

var numbers = new[] {1,2,3,4,5}; var reversed = numbers.Reverse(); Console.WriteLine(string.Join(",", reversed.ToArray())); //5,4,3,2,1

var mixed = new object[] {1,"Foo",2,"Bar",3,"Fizz",4,"Buzz"}; var numbers = mixed.OfType<int>(); Console.WriteLine(string.Join(",", numbers.ToArray())); //1,2,3,4

var numbers = new[] {1,2,3,4}; var averageNumber = numbers.Average(); Console.WriteLine(averageNumber); // 2,5 This method calculates the average of enumerable of numbers. var cities = new[] { new {Population = 1000}, new {Population = 2000}, new {Population = 4000} }; v...

var names = new[] {"Foo","Bar","Fizz","Buzz"}; var thirdName = names.ElementAt(2); Console.WriteLine(thirdName); //Fizz //The following throws ArgumentOutOfRangeException var minusOnethName = names.ElementAt(-1); var fifthName = names.ElementAt(4); ...

var names = new[] {"Foo","Bar","Fizz","Buzz"}; var thirdName = names.ElementAtOrDefault(2); Console.WriteLine(thirdName); //Fizz var minusOnethName = names.ElementAtOrDefault(-1); Console.WriteLine(minusOnethName); //null var fifthName = names.Eleme...

var numbers = new[] {2,4,6,8,1,3,5,7}; var oddNumbers = numbers.SkipWhile(n => (n & 1) == 0); Console.WriteLine(string.Join(",", oddNumbers.ToArray())); //1,3,5,7

var numbers = new[] {2,4,6,1,3,5,7,8}; var evenNumbers = numbers.TakeWhile(n => (n & 1) == 0); Console.WriteLine(string.Join(",", evenNumbers.ToArray())); //2,4,6

var numbers = new[] {2,4,6,8,1,3,5,7}; var numbersOrDefault = numbers.DefaultIfEmpty(); Console.WriteLine(numbers.SequenceEqual(numbersOrDefault)); //True var noNumbers = new int[0]; var noNumbersOrDefault = noNumbers.DefaultIfEmpty(); Console.WriteLine(noNumbersOrDefault.Count()); //1 C...

Generating a new object in each step: var elements = new[] {1,2,3,4,5}; var commaSeparatedElements = elements.Aggregate( seed: "", func: (aggregate, element) => $"{aggregate}{element},"); Console.WriteLine(commaSeparatedElements); //1,2,3,4,5, Using th...

Returns the Type of an object, without the need to instantiate it. Type type = typeof(string); Console.WriteLine(type.FullName); //System.String Console.WriteLine("Hello".GetType() == type); //True Console.WriteLine("Hello".GetType() == typeof(string)); //True

The namespace keyword is an organization construct that helps us understand how a codebase is arranged. Namespaces in C# are virtual spaces rather than being in a physical folder. namespace StackOverflow { namespace Documentation { namespace CSharp.Keywords { ...

public interface IAnimal { string Name { get; set; } } public interface INoiseMaker { string MakeNoise(); } public class Cat : IAnimal, INoiseMaker { public Cat() { Name = "Cat"; } public string Name { get; set; } public string M...

public class LivingBeing { string Name { get; set; } } public interface IAnimal { bool HasHair { get; set; } } public interface INoiseMaker { string MakeNoise(); } //Note that in C#, the base class name must come before the interface names public class Cat : LivingBei...

interface BaseInterface {} class BaseClass : BaseInterface {} interface DerivedInterface {} class DerivedClass : BaseClass, DerivedInterface {} var baseInterfaceType = typeof(BaseInterface); var derivedInterfaceType = typeof(DerivedInterface); var baseType = typeof(BaseClass); var derived...

using System; using BasicStuff = System; using Sayer = System.Console; using static System.Console; //From C# 6 class Program { public static void Main() { System.Console.WriteLine("Ignoring usings and specifying full type name"); Console.WriteLine(&quot...

using System; using System.IO; using System.Net; using System.Net.Sockets; using System.Text; class TcpChat { static void Main(string[] args) { if(args.Length == 0) { Console.WriteLine("Basic TCP chat"); Console.WriteLine(); ...

Immediately pass control to the next iteration of the enclosing loop construct (for, foreach, do, while): for (var i = 0; i < 10; i++) { if (i < 5) { continue; } Console.WriteLine(i); } Output: 5 6 7 8 9 Live Demo on .NET Fiddle var stuff = new [] ...