"Hello, World" with Command-Line and Visual Studio Code

In this tutorial, you will create a cross-platform desktop application using C#, .NET command line tools, and Visual Studio Code. The application will display a message box in response to a button click.

Prerequisites

1. Download and install .NET SDK. The minimum supported SDK version is .NET 6.0.
2. Install AlterNET UI project templates by running

   dotnet new install Alternet.UI.Templates
   

3. Download and install Visual Studio Code
4. In Visual Studio Code, ensure the C# extension is installed. For information about how to install extensions on Visual Studio Code, see VS Code Extension Marketplace.
5. If you develop under Linux, please install required packages as described at the end of this page.

Create New Project

1. Create a new directory for your application; name it HelloWorld
2. Open the Command Prompt window (Terminal on macOS or Linux)
3. Navigate the terminal to the created directory:

   cd path/to/HelloWorld
   

4. Enter the following command to create a new project in the current directory:

   dotnet new alternet-ui
   

5. The following files will be created:

   HelloWorld.csproj
   MainWindow.uixml
   MainWindow.uixml.cs
   Program.cs
   

6. Compile and run the created project by executing:

   dotnet run
   

The application will start and display its window:

Note

By default, the created project will use .NET 6.0 as a target framework. If .NET 6.0 runtime is not installed on your machine, you will be prompted to do so on the first application run.

Note

You can also create .cs/.uixml files for a new window from the console like this:

dotnet new alternet-ui-window -n MyNewWindow --namespace Test1

Where MyNewWindow is a name for a new window class, and Test1 is the created class namespace name.

Open Project with Visual Studio Code

1. Start Visual Studio Code.

2. Select File > Open Folder (File > Open... on macOS) from the main menu.

3. In the Open Folder dialog, locate a HelloWorld folder and click Select Folder (Open on macOS).

4. The popup prompting Select 1 of 2 projects will appear at the top of the screen:

   

   Select All contained projects.

5. After several seconds, a popup dialog with the message Required assets to build and debug are missing from 'HelloWorld'. Add them? will appear at the bottom-right corner of the screen:

   

   Select Yes. The .vscode subdirectory will be created with the workspace settings automatically set up.

6. Now, you can debug your application by pressing F5 or run it without debugging by pressing Ctrl+F5. The application will be built automatically if required.

7. Open MainWindow.uixml by clicking the corresponding item in the VS Code Explorer panel. In the editor, change the Title attribute value from "HelloWorld" to "My First Application":

   <Window xmlns="http://schemas.alternetsoft.com/ui/2021"
           xmlns:x="http://schemas.alternetsoft.com/ui/2021/uixml"
           x:Class="HelloWorld.MainWindow"
           Title="My First Application">
   </Window>
   

8. Press Ctrl+F5 to build and run the application and see its window title has changed accordingly.

Note

For information and tutorials on general C# development and debugging with Visual Studio Code, see the corresponding MSDN article.

Add Button to the Window

1. In MainWindow.uixml, add the following markup:

   <Window xmlns="http://schemas.alternetsoft.com/ui/2021"
           xmlns:x="http://schemas.alternetsoft.com/ui/2021/uixml"
           x:Class="HelloWorld.MainWindow"
           Title="My First Application">
     <StackPanel>
       <Button Name="helloButton" Text="Say Hello" Margin="20" />
     </StackPanel>
   </Window>
   

2. Run the application by pressing Ctrl+F5:

   

Write Code to Respond to the Button Click

1. In MainWindow.uixml, add the Click attribute to the Button element like the following:

   <Window xmlns="http://schemas.alternetsoft.com/ui/2021"
           xmlns:x="http://schemas.alternetsoft.com/ui/2021/uixml"
           x:Class="HelloWorld.MainWindow"
           Title="My First Application">
     <StackPanel>
       <Button Name="helloButton" Text="Say Hello" Margin="20" Click="HelloButton_Click" />
     </StackPanel>
   </Window>
   

   This will bind the Click event to its handler, ' HelloButton_Click`.

2. In MainWindow.uixml.cs file, add the following HelloButton_Click method:

   using System;
   using Alternet.UI;
   
   namespace HelloWorld
   {
       public partial class MainWindow : Window
       {
           public MainWindow()
           {
               InitializeComponent();
           }
   
           private void HelloButton_Click(object? sender, EventArgs e)
           {
               MessageBox.Show("Hello, world!");
           }
       }
   }
   

3. Run the application, then click Say Hello button. The message box appears:

   

Note

The application created in this tutorial can be compiled and run without source code modifications on all the supported platforms: Windows, macOS, and Linux.

Linux

Before running Alternet.UI applications on Linux, you need to install required packages. There is special installation script for Ubuntu. You can download it from the GitHub repository (File: Install.Scripts/Ubuntu.Install.Packages.sh). This is development packages, end-users do not need to install all of them.

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Congratulations, you have completed the "Hello, World" tutorial using command line tools and Visual Studio Code.

For a similar tutorial but using Visual Studio on Windows, see "Hello, World" with Visual Studio.