Developer’s Guide to Collections in Microsoft® .NET

Chapter 7. Introduction to LINQ

After completing this chapter, you will be able to

• Understand what LINQ is.

• Write LINQ queries against collection classes.

What Is LINQ?

In the previous chapters, you saw how to create and interact with collections using the foreach statement and Microsoft .NET interfaces. In this chapter, you will discover a different approach: how to query your collections with the Language Integrated Query (LINQ). With LINQ, you can query data by using native language syntax.

Here’s an example that does not use LINQ.

C#

Random rnd = new Random(); List<int> randomNumbers = new List<int>(); for (int i = 0; i < 10; i++) { randomNumbers.Add(rnd.Next(100)); } List<int> sortedNumbers = new List<int>(randomNumbers); sortedNumbers.Sort(); sortedNumbers.Reverse(); ...