Book Image

C# 7.1 and .NET Core 2.0 ??? Modern Cross-Platform Development - Third Edition

By : Mark J. Price
Book Image

C# 7.1 and .NET Core 2.0 ??? Modern Cross-Platform Development - Third Edition

By: Mark J. Price

Overview of this book

C# 7.1 and .NET Core 2.0 – Modern Cross-Platform Development, Third Edition, is a practical guide to creating powerful cross-platform applications with C# 7.1 and .NET Core 2.0. It gives readers of any experience level a solid foundation in C# and .NET. The first part of the book runs you through the basics of C#, as well as debugging functions and object-oriented programming, before taking a quick tour through the latest features of C# 7.1 such as default literals, tuples, inferred tuple names, pattern matching, out variables, and more. After quickly taking you through C# and how .NET works, this book dives into the .NET Standard 2.0 class libraries, covering topics such as packaging and deploying your own libraries, and using common libraries for working with collections, performance, monitoring, serialization, files, databases, and encryption. The final section of the book demonstrates the major types of application that you can build and deploy cross-device and cross-platform. In this section, you'll learn about websites, web applications, web services, Universal Windows Platform (UWP) apps, and mobile apps. 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.
Table of Contents (31 chapters)
Title Page
Credits
About the Author
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface
2
Part 1 – C# 7.1
8
Part 2 – .NET Core 2.0 and .NET Standard 2.0
16
Part 3 – App Models
22
Summary
Index

Creating your own LINQ extension methods


In Chapter 6, Implementing Interfaces and Inheriting Classes, you learned how to create your own extension methods. To create LINQ extension methods, all you must do is extend the IEnumerable<T> type.

Note

Good PracticePut your own extension methods in a separate class library so that they can be easily deployed as their own assembly or NuGet package.

In either Visual Studio 2017 or Visual Studio Code, open the LinqWithEFCore project or folder, and add a new class file named MyLINQExtensions.cs.

We will look at the Average extension method as an example. Any school child will tell you that average can mean one of three things:

  • Mean: Sum the numbers and divide by the count
  • Mode: The most common number
  • Median: The number in the middle of the numbers when ordered

The Average extension method actually calculates the mean. We might want to define our own extension methods for mode and median.

Modify the class to look like the following code:

using System.Collections...