Tutorial by Examples: u

To make a class support collection initializers, it must implement IEnumerable interface and have at least one Add method. Since C# 6, any collection implementing IEnumerable can be extended with custom Add methods using extension methods. class Program { static void Main() { va...

Extension methods are static methods which behave like instance methods. However, unlike what happens when calling an instance method on a null reference, when an extension method is called with a null reference, it does not throw a NullReferenceException. This can be quite useful in some scenarios....

string sqrt = "\u221A"; // √ string emoji = "\U0001F601"; // 😁 string text = "\u0022Hello World\u0022"; // "Hello World" string variableWidth = "\x22Hello World\x22"; // "Hello World"

You are allowed to create and throw exceptions in your own code. Instantiating an exception is done the same way that any other C# object. Exception ex = new Exception(); // constructor with an overload that takes a message string Exception ex = new Exception("Error message"); Yo...

The ?. operator is syntactic sugar to avoid verbose null checks. It's also known as the Safe navigation operator. Class used in the following example: public class Person { public int Age { get; set; } public string Name { get; set; } public Person Spouse { get; set; } } If a...

Similarly to the ?. operator, the null-conditional index operator checks for null values when indexing into a collection that may be null. string item = collection?[index]; is syntactic sugar for string item = null; if(collection != null) { item = collection[index]; }

// assign string from a string literal string s = "hello"; // assign string from an array of characters char[] chars = new char[] { 'h', 'e', 'l', 'l', 'o' }; string s = new string(chars, 0, chars.Length); // assign string from a char pointer, derived from a string string s; uns...

// single character s char c = 's'; // character s: casted from integer value char c = (char)115; // unicode character: single character s char c = '\u0073'; // unicode character: smiley face char c = '\u263a';

// assigning a signed short to its minimum value short s = -32768; // assigning a signed short to its maximum value short s = 32767; // assigning a signed int to its minimum value int i = -2147483648; // assigning a signed int to its maximum value int i = 2147483647; // assigning a s...

// assigning an unsigned short to its minimum value ushort s = 0; // assigning an unsigned short to its maximum value ushort s = 65535; // assigning an unsigned int to its minimum value uint i = 0; // assigning an unsigned int to its maximum value uint i = 4294967295; // assigning an...

In order to be able to manage your projects' packages, you need the NuGet Package Manager. This is a Visual Studio Extension, explained in the official docs: Installing and Updating NuGet Client. Starting with Visual Studio 2012, NuGet is included in every edition, and can be used from: Tools ->...

When you right-click a project (or its References folder), you can click the "Manage NuGet Packages..." option. This shows the Package Manager Dialog.

Click the menus Tools -> NuGet Package Manager -> Package Manager Console to show the console in your IDE. Official documentation here. Here you can issue, amongst others, install-package commands which installs the entered package into the currently selected "Default project": Ins...

public class SomeClass { public void DoStuff() { } protected void DoMagic() { } } public static class SomeClassExtensions { public static void DoStuffWrapper(this SomeClass someInstance) { someInstance.DoStuff(); // ok ...

The ref and out keywords cause an argument to be passed by reference, not by value. For value types, this means that the value of the variable can be changed by the callee. int x = 5; ChangeX(ref x); // The value of x could be different now For reference types, the instance in the variable can...

You can enumerate through a Dictionary in one of 3 ways: Using KeyValue pairs Dictionary<int, string> dict = new Dictionary<int, string>(); foreach(KeyValuePair<int, string> kvp in dict) { Console.WriteLine("Key : " + kvp.Key.ToString() + ", Value : " +...

using System; using System.IO; using System.Linq; using System.Net.Http; using System.Threading.Tasks; class HttpGet { private static async Task DownloadAsync(string fromUrl, string toFile) { using (var fileStream = File.OpenWrite(toFile)) { using (va...

The checked and unchecked keywords define how operations handle mathematical overflow. "Overflow" in the context of the checked and unchecked keywords is when an integer arithmetic operation results in a value which is greater in magnitude than the target data type can represent. When ove...

public async Task<JobResult> GetDataFromWebAsync() { var nextJob = await _database.GetNextJobAsync(); var response = await _httpClient.GetAsync(nextJob.Uri); var pageContents = await response.Content.ReadAsStringAsync(); return await _database.SaveJobResultAsync(pageContents); } ...

When you want to catch an exception and do something, but you can't continue execution of the current block of code because of the exception, you may want to rethrow the exception to the next exception handler in the call stack. There are good ways and bad ways to do this. private static void AskTh...