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Hello, world!

Now that you've installed Calyxium, it's time to write your first Calyxium program. It's traditional when learning a new language to write a little program that prints the text Hello, world! to the screen, so we’ll do the same here!

Creating a Project Directory

You'll start by making a directory to store your Calyxium code. It doesn't matter to Calyxium where your code lives, but for the exercises and projects in this book, we suggest making a projects directory in your home directory and keeping all your projects there.

Open a terminal and enter the following commands to make a projects directory and a directory for the “Hello, world!” project within the projects directory.

For Linux, macOS and PowerShell on Windows, enter this

$ mkdir ~/projects
$ cd ~/projects
$ mkdir hello_world
$ cd hello_world

For Windows CMD, enter this:

> mkdir "%USERPROFILE%\projects"
> cd /d "%USERPROFILE%\projects"
> mkdir hello_world
> cd hello_world

Writing and Running a Calyxium Program

Next, make a new source file and call it main.cx. Calyxium files always end with the .cx extension. If you’re using more than one word in your filename, the convention is to use an underscore to separate them. For example, use hello_world.cx rather than helloworld.cx.

Now open the main.cx file you just created and enter the code in listed below.

print("Hello, world!")

Save the file and go back to your terminal in the ~/projects/hello_world directory. Enter the following commands to run the file:

$ calyxium main.cx
Hello, world!

Regardless of your operating system, the string Hello, world! should print to the terminal.

If Hello, world! did print, congratulations! You’ve officially written a Calyxium program. That makes you a Calyxium programmer. Welcome to the club!

Let’s review this “Hello, world!” program in detail.

print("Hello, world!")

This line does all the work in this little program: it prints text to the screen. There are two important details to notice here.

  • print calls the function to display contents to your terminal.

  • You see the "Hello, world!" string. We pass this string as an argument to print, and the string is printed to the screen.

  • Unlike in Python, print does not automatically add a newline (\n) at the end. If you want a line break, you’ll need to include \n yourself.