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)

Pattern matching with regular expressions

Regular expressions are useful for validating input from the user. They are very powerful and can get very complicated. Almost all programming languages have support for regular expressions and use a common set of special characters to define them:

  1. Create a new console application project named WorkingWithRegularExpressions, add it to the workspace, and select it as the active project for OmniSharp.
  2. At the top of the file, import the following namespace:
    using System.Text.RegularExpressions; 

Checking for digits entered as text

Let's implement the common example of validating number input:

  1. In the Main method, add statements to prompt the user to enter their age and then check that it is valid using a regular expression that looks for a digit character, as shown in the following code:
    Write("Enter your age: "); 
    string input = ReadLine();
    var ageChecker = new Regex...