Book Image

C# 6 and .NET Core 1.0

Book Image

C# 6 and .NET Core 1.0

Overview of this book

With the release of .NET Core 1.0, you can now create applications for Mac OS X and Linux, as well as Windows, using the development tools you know and love. C# 6 and .NET Core 1.0 has been divided into three high-impact sections to help start putting these new features to work. First, we'll run you through the basics of C#, as well as object-orient programming, before taking a quick tour through the latest features of C# 6 such as string interpolation for easier variable value output, exception filtering, and how to perform static class imports. We'll also cover both the full-feature, mature .NET Framework and the new, cross-platform .NET Core. After quickly taking you through C# and how .NET works, we'll dive into the internals of the .NET class libraries, covering topics such as performance, monitoring, debugging, internationalization, serialization, and encryption. We'll look at Entity Framework Core 1.0 and how to develop Code-First entity data models, as well as how to use LINQ to query and manipulate that data. The final section will demonstrate the major types of applications that you can build and deploy cross-device and cross-platform. In this section, we'll cover Universal Windows Platform (UWP) apps, web applications, and web services. Lastly, we'll help you build a complete application that can be hosted on all of today's most popular platforms, including Linux and Docker. By the end of the book, you'll be armed with all the knowledge you need to build modern, cross-platform applications using C# and .NET Core.
Table of Contents (25 chapters)
C# 6 and .NET Core 1.0
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Casting within inheritance hierarchies


Casting is subtly different from converting between different types.

Implicit casting

In the previous example, you saw how an instance of a derived type can be stored in a variable of its base type (or its base's base type and so on). When we do this, it is called implicit casting.

Explicit casting

Going the other way, for example, attempting to store an instance of a base type in a variable of a derived type, is an explicit cast and you must use parentheses to do it.

In the Main method, add the following code:

Employee e2 = aliceInPerson;

Visual Studio gives a compile error, as shown in the following screenshot:

Change the code as follows:

Employee e2 = (Employee)aliceInPerson;

Handling casting exceptions

The compiler is now happy but because aliceInPerson might be a different derived type, such as a Student instead of an Employee, we need to be careful. This statement might throw an InvalidCastException.

We can handle this by writing a try-catch statement, but...