Shulou(Shulou.com)06/02 Report--

This article mainly explains "what is the extension method of Linq". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is the extension method of Linq".

LINQ makes querying a first-class programming concept in A. NET, and the data being queried can be XML (LINQ to XML), Databases (LINQ to SQL, LINQ to Dataset, LINQ to Entities), and LINQ to Objects. LINQ is also extensible, allowing you to create custom LINQ data providers (such as LINQ to Amazon, LINQ to NHibernate, LINQ to LDAP). Here I will discuss some of the new language features and improvements in Cellular 3.0 that make LINQ so powerful.

Linq extension method

The Linq extension method allows you to extend an existing type and add its methods without inheriting it or recompiling it. So unlike writing helper methods for an object, Linq extension methods can be directly part of the object itself.

As an example, suppose we want to verify that a string is a valid Email address, we can write a method that enters it as a string and returns true or false. Now, using the Linq extension method, we can do this as follows:

Publicstatic class MyExtensions {publicstatic bool IsValidEmailAddress (this strings) {Regex regex = new Regex (@ "^ [w -] + @ ([w -] +.) + [w -] {2yre 4} $"); return regex.IsMatch (s);}}

We define a static class with static methods. Note that the static method has a this keyword before the parameter type string, which tells the compiler that this particular Linq extension method will be added to objects of type string. So we can call this member method in string:

Using MyExtensions; string email = Request.QueryString ["email"]; if (email.IsValidEmailAddress ()) {/ /...}

It is worth mentioning that LINQ uses Linq extension methods in the System.Linq namespace (such as where (), orderby (), select (), sum (), average (), and so on), and it defines standard query operators that can be used to query relational databases, XML, and any .NET object that implements the IEnumerable interface.

Thank you for your reading, the above is the content of "what is the Linq extension method", after the study of this article, I believe you have a deeper understanding of what the Linq expansion method is, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.