Tutorial by Examples: u

var oneNumber = new[] {5}; var theOnlyNumber = oneNumber.SingleOrDefault(); Console.WriteLine(theOnlyNumber); //5 var numbers = new[] {1,2,3,4,5}; var theOnlyNumberSmallerThanTwo = numbers.SingleOrDefault(n => n < 2); Console.WriteLine(theOnlyNumberSmallerThanTwo); //1 var theOnl...

var numbers = new[] {1,2,3,4,5}; var firstNumber = numbers.FirstOrDefault(); Console.WriteLine(firstNumber); //1 var firstEvenNumber = numbers.FirstOrDefault(n => (n & 1) == 0); Console.WriteLine(firstEvenNumber); //2 var firstNegativeNumber = numbers.FirstOrDefault(n => n < ...

For classes, interfaces, delegate, array, nullable (such as int?) and pointer types, default(TheType) returns null: class MyClass {} Debug.Assert(default(MyClass) == null); Debug.Assert(default(string) == null); For structs and enums, default(TheType) returns the same as new TheType(): struct...

var numbers = new[] {1,2,3,4}; var sumOfAllNumbers = numbers.Sum(); Console.WriteLine(sumOfAllNumbers); //10 var cities = new[] { new {Population = 1000}, new {Population = 2500}, new {Population = 4000} }; var totalPopulation = cities.Sum(c => c.Population); Console.Wr...

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 persons = new[] { new { Name="Fizz", Job="Developer"}, new { Name="Buzz", Job="Developer"}, new { Name="Foo", Job="Astronaut"}, new { Name="Bar", Job="Astronaut"}, }; var groupedByJob = person...

var numbers1to5 = new[] {1,2,3,4,5}; var numbers4to8 = new[] {4,5,6,7,8}; var numbers1to8 = numbers1to5.Union(numbers4to8); Console.WriteLine(string.Join(",", numbers1to8)); //1,2,3,4,5,6,7,8 Note that duplicates are removed from the result. If this is undesirable, use Concat ...

IEnumerable<int> numbers = new[] {1,2,3,4,5,6,7,8,9,10}; var numbersCount = numbers.Count(); Console.WriteLine(numbersCount); //10 var evenNumbersCount = numbers.Count(n => (n & 1) == 0); Console.WriteLine(evenNumbersCount); //5

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 numbersOrDefault = numbers.DefaultIfEmpty(); Console.WriteLine(numbers.SequenceEqual(numbersOrDefault)); //True var noNumbers = new int[0]; var noNumbersOrDefault = noNumbers.DefaultIfEmpty(); Console.WriteLine(noNumbersOrDefault.Count()); //1 C...

var persons = new[] { new { Name="Fizz", Job="Developer"}, new { Name="Buzz", Job="Developer"}, new { Name="Foo", Job="Astronaut"}, new { Name="Bar", Job="Astronaut"}, }; var groupedByJob = person...

class Developer { public int Id { get; set; } public string Name { get; set; } } class Project { public int DeveloperId { get; set; } public string Name { get; set; } } var developers = new[] { new Developer { Id = 1, Name = "Foobuzz" ...

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...

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...

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 [] ...

Using the null-coalescing operator (??) allows you to specify a default value for a nullable type if the left-hand operand is null. string testString = null; Console.WriteLine("The specified string is - " + (testString ?? "not provided")); Live Demo on .NET Fiddle This is l...

using is syntactic sugar that allows you to guarantee that a resource is cleaned up without needing an explicit try-finally block. This means your code will be much cleaner, and you won't leak non-managed resources. Standard Dispose cleanup pattern, for objects that implement the IDisposable interf...

The using static [Namespace.Type] directive allows the importing of static members of types and enumeration values. Extension methods are imported as extension methods (from just one type), not into top-level scope. 6.0 using static System.Console; using static System.ConsoleColor; using static ...

Overloading just equality operators is not enough. Under different circumstances, all of the following can be called: object.Equals and object.GetHashCode IEquatable<T>.Equals (optional, allows avoiding boxing) operator == and operator != (optional, allows using operators) When overrid...