Skip to main content

C# Extension Methods


Extension Methods in C#


Extension methods allow you to add methods to an existing type without changing then existing type or creating a new derived type.


The most common extension method in the LINQ operators added to the existing System.Collections.IEnumerable types.


To use standard query operators for most of the <IEnumerable> types add the using directive in your file,


using System.Linq;  (You may also need to add a reference to System.Core.dll)

class ExtensionMethods2

{

      static void Main()

     {

           int[] ints = { 10, 45, 15, 39, 21, 26 };

           var result = ints.OrderBy(g => g); 

           foreach (var i in result) { System.Console.Write(i + " "); }

     }

}

//Output: 10 15 21 26 39 45


Extension methods are created as non-generic static methods but called by instance method syntax.


namespace ExtensionMethods

{

    public static class MyExtensions

    {

           public static int WordCount(this String str)

          {

                return str.Split(new char[] { ' ', '.', '?' }, StringSplitOptions.RemoveEmptyEntries).Length;

          }

    }

}


The WordCount extension method defined for System.String class can be called in the application as below,


using ExtensionMethods;

string s = "This is a string";

int count = s.WordCount();


Note -  When creating extension methods for a type, if the signature is the same as the method in the type then it won't be invoked.






Labels

Labels:

Comments

Post a Comment

Popular posts from this blog

How to clear Visual Studio Cache

How to clear visual studio cache Many times, during development you would face situations where project references are not loaded properly or you get missing/error DLL's. This is because the Component cache gets corrupted randomly and without any warnings. The first option that needs to be done is to clear component cache and restart Visual Studio since the Cache might be holding onto previous DLL versions. Here are the steps on how to clear Visual Studio Cache, Clearing Component Cache: Close all Visual Studio Instances running in your machine. Also, make sure devenv.exe is not running in the Task Manager Delete the Component cache directory - %USERPROFILE%\AppData\Local\Microsoft\VisualStudio\1x.0\ComponentModelCache Restart Visual Studio The above steps should fix the cache issue most of the times, but some times that is not enough and you need to perform the below steps as well. Clearing User's Temp Folder: Open the temp folder in this locatio n -  %USERPROFILE%\AppData\Loc...
232 comments
Read more

How to dependency inject to static class

.Net core supports dependency injection. There are many ways that you can inject services like constructor injection, action method injection, property injection. But there will be scenarios where you need to inject dependency services to static classes. For example, injecting services to extension methods. First, create a static class with a one property IServiceProvider type public void ConfigureServices(IServiceCollection services) { services.AddScoped<ILoggerEntry, LoggerEntry>(); services.AddTransient<IMongoRepository, MongoRepository>(); } Second, configure your services in ConfigureServices() method in Startup.cs and define the lifetime of the service instance using either Transient, Scoped or Singleton types. public void ConfigureServices(IServiceCollection services) { services.AddScoped<ILoggerEntry, LoggerEntry>(); services.AddTransient<IMongoRepository, MongoRepository>(); } For the next step to configure the Static class provider proper...
1 comment
Read more

Error NU1605 - Detected package downgrade. Reference the package directly from the project to select a different version.

Error NU1605 - Detected package downgrade This error occurs when a dependency package has a version higher than an existing package version in the project solution. Solution: Add the following in .csproj file < PackageReference > < NoWarn >$( NoWarn ); NU1605 </ NoWarn > </ PackageReference > Another way to do this is to right-click on the solution and  click  Properties . Click  Build  and under  Errors and warnings  add 1605 to the  SuppressWarnings  text box. You can also add multiple error codes that you want to suppress by adding each separated by a comma. P.S. The below screenshot is in VS2019 Mac Version
Post a Comment
Read more