Book Image

C# 9 and .NET 5 – Modern Cross-Platform Development - Fifth Edition

By : Mark J. Price
Book Image

C# 9 and .NET 5 – Modern Cross-Platform Development - Fifth Edition

By: Mark J. Price

Overview of this book

In C# 9 and .NET 5 – Modern Cross-Platform Development, Fifth Edition, expert teacher Mark J. Price gives you everything you need to start programming C# applications. This latest edition uses the popular Visual Studio Code editor to work across all major operating systems. It is fully updated and expanded with a new chapter on the Microsoft Blazor framework. The book’s first part teaches the fundamentals of C#, including object-oriented programming and new C# 9 features such as top-level programs, target-typed new object instantiation, and immutable types using the record keyword. Part 2 covers the .NET APIs, for performing tasks like managing and querying data, monitoring and improving performance, and working with the file system, async streams, serialization, and encryption. Part 3 provides examples of cross-platform apps you can build and deploy, such as websites and services using ASP.NET Core or mobile apps using Xamarin.Forms. The best type of application for learning the C# language constructs and many of the .NET libraries is one that does not distract with unnecessary application code. For that reason, the C# and .NET topics covered in Chapters 1 to 13 feature console applications. In Chapters 14 to 20, having mastered the basics of the language and libraries, you will build practical applications using ASP.NET Core, Model-View-Controller (MVC), and Blazor. By the end of the book, you will have acquired the understanding and skills you need to use C# 9 and .NET 5 to create websites, services, and mobile apps.
Table of Contents (23 chapters)

Working with records

Before we dive into the new records language feature of C# 9, let us see some other related new features.

Init-only properties

You have used object initialization syntax to instantiate objects and set initial properties throughout this chapter. Those properties can also be changed after instantiation.

Sometimes you want to treat properties like readonly fields so they can be set during instantiation but not after. The new init keyword enables this. It can be used in place of the set keyword:

  1. In the PacktLibrary9 folder, add a new file named Records.cs.
  2. In the Records.cs file, define an immutable person class, as shown in the following code:
    namespace Packt.Shared
      public class ImmutablePerson
        public string FirstName { get; init; }
        public string LastName { get; init; }
  3. In Program.cs, at the bottom of the Main method, add statements to instantiate a new immutable person and then try to change...