How to use delegates in C#

A simple guide to using delegates in C#. It should be suitable for anybody but is particularly aimed at C/C++ programmers who are more used to using function pointers and function objects as a means of passing function parameters. For the C/C++ equivalent of using callbacks see this link: https://www.technical-recipes.com/2016/how-to-write-callbacks-in-c/ Step 1: declare the delegate [code language="csharp"] public delegate int Transform(int value); [/code] Step 2: create methods for the delegate [code language="csharp"] public int DoubleValue(int value) { return value * 2; } public int SquareValue(int value) { return value * value; } [/code] Step 3: Instantiate the delegate and use it [code language="csharp"] TransformValue doubleValue = DoubleValue; [/code] Full Code listing showing example usage [code language="csharp"] using System; namespace Delegates { internal class Program { #region Delegates public delegate int TransformValue(int value); #endregion public static int DoubleValue(int value) { return value * 2; } public static int SquareValue(int value) { return value * value; } private static void Main(string[] args) { TransformValue doubleValue = DoubleValue; TransformValue squareValue = SquareValue; const int Value = 10; Console.WriteLine("Value doubled = " + doubleValue(Value)); Console.WriteLine("Value doubled = " + squareValue(Value)); } } } [/code] Giving the following output as follows: delegate

Comments

Post a Comment

Popular posts from this blog

Using the Supervisor Controller Pattern to access View controls in MVVM

Image
As discussed on a StackOverflow post , this is considered bad practice, so only use this when necessary. Step 1: Create a new WPF project Step 2: Add event handling code A number of classes are needed for doing command bindings in MVVM. Create the following classes and add to your Visual Studio project: RelayCommand.cs [code language="csharp"] using System; using System.Windows.Input; namespace SupervisorControllingPattern { public class RelayCommand<T> : ICommand { private readonly Predicate<T> _canExecute; private readonly Action<T> _execute; public RelayCommand(Action<T> execute) : this(execute, null) { _execute = execute; } public RelayCommand(Action<T> execute, Predicate<T> canExecute) { if (execute == null) throw new ArgumentNullException(nameof(execute)); _execute = execute; _canExecute = canExecute; ...
Read more

Getting started with Tesseract optical character recognition (OCR) library in Visual Studio

Image
This post is a how-to guide on how to get up and running with using the tesseract optical character recognition (OCR) library in a Microsoft Visual Studio environment. The original link can be found at the following github location: https://tesseract-ocr.github.io/tessdoc/Compiling.html#windows Step 1: Build the latest library (using Software Network client) Download and extract the latest SW (Software Network https://software-network.org/) client from the following location: https://software-network.org/client/sw-master-windows-client.zip Open a DOS command prompt and run the following commands: [code language="xml"] sw setup sw build org.sw.demo.google.tesseract.tesseract-master [/code] As shown in the following screenshot: Step 2: Install git if you have not already done so You will need git to download the libraries needed for this project. Download link for obtaining the git for Windows executables etc here: https://git-scm.com/download/win...
Read more

How to send an e-mail via Google SMTP using C#

Image
First things first, some useful StackOverflow links: https://stackoverflow.com/questions/9201239/send-e-mail-via-smtp-using-c-sharp https://stackoverflow.com/questions/17462628/the-server-response-was-5-7-0-must-issue-a-starttls-command-first-i16sm1806350 To demonstrate how this is done I first create a new Visual Studio project: Some example code for sending an email via a Google email account (smtp.goolgle.com) - obviously replace this with email / credentials of your own... I put the code within a try-catch block in order to capture any errors that may occur while attempting this. [code language="csharp"] using System; using System.Net; using System.Net.Mail; namespace EmailSmtp { class Program { static void Main(string[] args) { try { // Credentials var credentials = new NetworkCredential("someEmail@gmail.com", "somePassword"); // Mail message var ...
Read more