Skip to main content

What Are New Features in C# 8.0? | C# 8 Features in VS 2019

What Are New Features in c# 8.0?

C# 8.0 adds the following features and enhancements to the C# language:
=>Read-only members
=>Default interface methods
=>Pattern matching enhancements:
          i) Witch expressions
          j) Property patterns
         k) Tuple patterns
         l) Positional patterns
=>Using declarations
=>Static local functions
=>Disposable ref structs
=>Nullable reference types
=>Asynchronous streams
=>Indices and ranges
=>Null-coalescing assignment
=>Unmanaged constructed types
=>Stackalloc in nested expressions
=>Enhancement of interpolated verbatim strings

You can see n-depth articles with examples –

Readonly Member  -
Provide a way to specify individual instance members on a struct do not modify state, in the same way that read-only struct specifies no instance members modify state. 

Allows you to apply the read-only modifier to any member of a struct.

public struct YValue
{
    private int Y { get; set; }
    public readonly int IncreaseY()
    {
        // This will not compile: C# 8
        Y = Y + 1;
        var newY = Y + 1; // OK
        return newY;
    }
}

Default Interface Methods  -

Allows you to add new functionality to your interfaces of your libraries and ensure the backward compatibility with code written for older versions of those interfaces.

interface IWriteLine
{
    public void WriteLine()
    {
        Console.WriteLine("Wow C# 8!");
    }
}

Pattern Matching Enhancements  -

Provides the ability to deconstruct matched objects, and giving you access to parts of their data structures.

 C# offers a rich set of patterns that can be used for matching:  
1.      Switch expressions
2.      Property patterns
3.      Tuple patterns
4.      Positional patterns

There are several syntax improvements here:
1.      The variable comes before the switch keyword. The different order makes it visually easy to distinguish the switch expression from the switch statement.
2.      The case and : elements are replaced with =>. It's more concise and intuitive.
3.      The default case is replaced with a _ discard.
4.      The bodies are expressions, not statements.

static bool Positive(Point p) => p switch
        {
            (0, 0) => true,
            (var x, var y) when x > 0 && y > 0 => true,
            _ => false
        };

Nullable Reference Types -

Emits a compiler warning or error if a variable that must not be null is assigned to null.

string? nullableString = null;
// WARNING: may be null! Take care!
 Console.WriteLine(nullableString.Length)

The goal of this feature is to:

Allow developers to express whether a variable, parameter or result of a reference type is intended to be null or not.

Provide warnings when such variables, parameters and results are not used according to that intent.

Using Declarations  -

The language will add two new capabilities around the using statement in order to make resource management simpler: using should recognize a disposable pattern in addition to IDisposable and add a using declaration to the language.

Enhances the ‘using’ operator to use with Patterns and make it more natural.

using var repository = new Repository();
Console.WriteLine(repository.First());
// repository is disposed here!

Enhancement of interpolated verbatim strings

Order of the $ and @ tokens in interpolated verbatim strings can be any: both $@"..." and @$"..." are valid interpolated verbatim strings. In earlier C# versions, the $ token must appear before the @ token.

Allows @$““as a verbatim interpolated string,
var file = @$"c:\temp\{filename}";

Asynchronous Streams  -

Starting with C# 8.0, you can create and consume streams asynchronously. A method that returns an asynchronous stream has three properties:

1) It's declared with the async modifier.
2) It returns an IAsyncEnumerable<T>.
3) The method contains yield return statements to return successive elements in the asynchronous stream.

Allows having enumerators that support async operations.

await foreach (var x in enumerable)
{
  Console.WriteLine(x);
}

Null-coalescing Assignment  -

C# 8.0 introduces the null-coalescing assignment operator ??=. You can use the ??= operator to assign the value of its right-hand operand to its left-hand operand only if the left-hand operand evaluates to null.

Simplifies a common coding pattern where a variable is assigned a value if it is null. It is common to see the code of the form:

//In C# 1 to 7
 if (variable == null)
 {
   variable = expression; 
 }

// In C# 8
variable ??= expression;

Static local functions

You can now add the static modifier to local functions to ensure that local function doesn't capture (reference) any variables from the enclosing scope. Allows you to add the 'static' modifier to the local functions.

int AddFiveAndSeven()
{
    int y = 1; int x = 2;
    return Add(x, y);

    static int Add(int o, int t) => o + t;
}

Unmanaged Constructed Types  -

Allows you to take a pointer to unmanaged constructed types, such as ValueTuple<int, int>, as long as all the elements of the generic type are unmanaged.

struct Foo<T> where T : unmanaged
{
}

public unsafe void Test()
{
    var foo = new Foo<int>();
    var bar = &foo;   // C# 8
}

Stackalloc in Nested Expressions

The result of a stackalloc expression is of the System.Span<T> or System.ReadOnlySpan<T> type.

Span<int> set = stackalloc[] { 1, 2, 3, 4, 5, 6};
var subSet = set.Slice(3, 2);

foreach (var n in subSet){
  Console.WriteLine(n);  // Output: 4  5
}

Disposable ref structs  -

A struct declared with the ref modifier may not implement any interfaces and so can't implement IDisposable. Therefore, to enable a ref struct to be disposed, it must have an accessible void Dispose() method. This feature also applies to read-only ref struct declarations.

Allows you to use the ‘using’ pattern with ref struct or readonly ref struct‘.

// Pattern-based using for ref struct
ref struct Test
{
    public void Dispose() { }
}
using var test = new Test();
// test is disposed here!
Indices and ranges  -
Indices and ranges provide a succinct syntax for accessing single elements or ranges in a sequence.

1) This language support relies on two new types, and two new operators:
2) System.Index represents an index into a sequence.
3) The index from end operator ^, which specifies that an index is relative to the end of the sequence.
4) System.Range represents a sub range of a sequence.
5) The range operator .., which specifies the start and end of a range as its operands.

Allows you to use more natural syntax for specifying subranges in an array or a collection.

int[] a = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

Index:  Used to obtain the collection from the beginning or from the end.

 // Number 4 from end of the collection
Index i2 = ^4;
Console.WriteLine($"{a[i2]}"); // "6"

//Range: Access a sub-collection(slice) from a collection.
var slice = a[i1..i2]; // { 3, 4, 5 }
By Anil Singh | Rating of this article (*****)

Popular posts from this blog

nullinjectorerror no provider for httpclient angular 17

In Angular 17 where the standalone true option is set by default, the app.config.ts file is generated in src/app/ and provideHttpClient(). We can be added to the list of providers in app.config.ts Step 1:   To provide HttpClient in a standalone app we could do this in the app.config.ts file, app.config.ts: import { ApplicationConfig } from '@angular/core'; import { provideRouter } from '@angular/router'; import { routes } from './app.routes'; import { provideClientHydration } from '@angular/platform-browser'; //This (provideHttpClient) will help us to resolve the issue  import {provideHttpClient} from '@angular/common/http'; export const appConfig: ApplicationConfig = {   providers: [ provideRouter(routes),  provideClientHydration(), provideHttpClient ()      ] }; The appConfig const is used in the main.ts file, see the code, main.ts : import { bootstrapApplication } from '@angular/platform-browser'; import { appConfig } from ...

List of Countries, Nationalities and their Code In Excel File

Download JSON file for this List - Click on JSON file    Countries List, Nationalities and Code Excel ID Country Country Code Nationality Person 1 UNITED KINGDOM GB British a Briton 2 ARGENTINA AR Argentinian an Argentinian 3 AUSTRALIA AU Australian an Australian 4 BAHAMAS BS Bahamian a Bahamian 5 BELGIUM BE Belgian a Belgian 6 BRAZIL BR Brazilian a Brazilian 7 CANADA CA Canadian a Canadian 8 CHINA CN Chinese a Chinese 9 COLOMBIA CO Colombian a Colombian 10 CUBA CU Cuban a Cuban 11 DOMINICAN REPUBLIC DO Dominican a Dominican 12 ECUADOR EC Ecuadorean an Ecuadorean 13 EL SALVA...

How To convert JSON Object to String?

To convert JSON Object to String - To convert JSON Object to String in JavaScript using “JSON.stringify()”. Example – let myObject =[ 'A' , 'B' , 'C' , 'D' ] JSON . stringify ( myObject ); ü   Stayed Informed –   Object Oriented JavaScript Interview Questions I hope you are enjoying with this post! Please share with you friends!! Thank you!!!

Encryption and Decryption Data/Password in Angular

You can use crypto.js to encrypt data. We have used 'crypto-js'.   Follow the below steps, Steps 1 –  Install CryptoJS using below NPM commands in your project directory npm install crypto-js --save npm install @types/crypto-js –save After installing both above commands it looks like  – NPM Command  1 ->   npm install crypto-js --save NPM Command  2 ->   npm install @types/crypto-js --save Steps 2  - Add the script path in “ angular.json ” file. "scripts" : [                "../node_modules/crypto-js/crypto-js.js"               ] Steps 3 –  Create a service class “ EncrDecrService ” for  encrypts and decrypts get/set methods . Import “ CryptoJS ” in the service for using  encrypt and decrypt get/set methods . import  {  Injectable  }  from ...

Angular Testing Questions and Answers | 9, 8, 7, 6

What Is Testing? The testing is a tools and techniques for a unit and integration testing Angular applications . Why Test? Tests are the best ways to prevent software bugs and defects. How to Setup Test in Angular Project? Angular CLI install everything you need to test an Angular application. This CLI command takes care of Jasmine and karma configuration for you. Run this CLI command- ng test The test file extension must be “.spec.ts” so that tooling can identify the test file. You can also unit test your app using other testing libraries and test runners. Types of Test – The all great developer knows his/her testing tools use. Understanding your tools for testing is essential before diving into writing tests. The Testing depends on your project requirements and the project cost. The types of Testing looks like - 1.       Unit Test 2.       Integration Test 3.       En...