Your First Program

Here are the steps needed to build your own program:

1. Create a new folder for the project, and move into this in the terminal
2. Use dotnet new console to create the initial project files
3. Add the SplashKit package we will be using dotnet add package splashkit
4. Write the code in Program.cs
5. Build and run using dotnet run

Let’s go through these steps to build a simple terminal-based program to output the text: “Hello, World”.

Why “Hello World”?

Whenever you start learning a new programming language, you will likely write code to output “Hello, World” for your first program - just like we are going to do here!

You can read more about the origin of “Hello, World” here if you’re curious, but the short version is that it is a simple way of checking that your computer is set up correctly to code in a particular language.

Make sure you are set up

We need somewhere to put our project’s code. For this, we will create a folder in our Documents/Code folder. You should have created this folder as part of the tour in the Computer Use chapter, but we will repeat it here just in case you missed that step.

You can choose anywhere to store your code, if you want to save your code elsewhere then make sure to adjust paths as needed. Open a terminal, and use the following commands to create the Documents/Code folder:

# Create a Documents/Code folder
# Windows users -see the following note

mkdir ~/Documents/Code

# Move to the Documents/Code folder
cd ~/Documents/Code

Note

If you are using MSYS2 MINGW64:

• You will need to adjust the mkdir and cd commands slightly from what is shown above if you want to use your standard Documents filder. With MSYS2, you need to use something like this:

  mkdir /c/Users/<your_username>/Documents/Code
  cd /c/Users/<your_username>/Documents/Code

  Replace <your_username> with your own username.

• To check your username, you can use the whoami command in your terminal.

Tip

You can also type cd (“cd”, then space), then drag a folder from File Explorer or Finder into your terminal window. This will add the path to the folder/file that you drag in.

Create the project folder

Now you can create a folder for your project. Make sure you are in your Documents/Code folder, and run the following commands:

# Make a folder for the project
mkdir HelloWorld

# Move into that folder
cd HelloWorld

Project Folders

Remember to avoid adding Spaces in your folder names!

Create dotnet project files

We will be using C# initially, for these programs we need to setup project files that the language uses to know how to build your program.

To create the initial project files for this C# program, copy and paste the following commands into your Terminal window:

dotnet new console
dotnet add package splashkit

This creates the project, and add the splashkit library we will be using.

If you run ls -lha in the terminal after the commands above, it should look similar to this:

Image not subject to The Programmer's Field Guide CC BY-NC-ND 4.0 License

Now you are ready to start coding your first program!

Write your code

From the terminal window, we can open the current folder in Visual Studio Code using the following command:

code .

Note

If the code . command does not work on your computer, you can open Visual Studio Code, and then click File > Open Folder, and then navigate to the HelloWorld folder you created in the steps above. Make sure to open the folder itself.

You will notice that shortly after opening the project, a bin folder and a .sln file will be added automatically:

Image not subject to The Programmer's Field Guide CC BY-NC-ND 4.0 License

Open Program.cs file (shown above in Green box) by double-clicking the file in the Explorer tab (shown above in Orange box):

Copy the following code into your Program.cs file (replacing the existing code):

using static SplashKitSDK.SplashKit;

WriteLine("Hello, World!");

After the last line, you can add another WriteLine("...") bit of code with your own custom message!

Caution

We will be using SplashKit for terminal input and output initially. Avoid using the System.Console version for now, but we will come back to this once we have moved beyond the basics.

Build and run your code

Let’s turn your code into a program! Like magic!

Use the following command to build and run the program:

dotnet run

Use the Terminal inside VS Code!

To avoid having to switch back and forth between your apps, you can open a Terminal shell inside Visual Studio Code by clicking “Terminal” (one of the tabs across the top of the window/screen), and then click on “New Terminal”.

Here is what the result will look like:

Image not subject to The Programmer's Field Guide CC BY-NC-ND 4.0 License

Next, we are going to create a Graphical Hello World program!