Hello, world

At this point we're ready to start writing in PHP. Make a new folder for your PHP code.

If you have a favourite text editor or integrated development environment, such as Vim, Atom, or VS Code you may want to stick with that, but the best tool for editing PHP code is almost certainly JetBrains' PhpStorm. PhpStorm is free for 30 days, but will demand money after that.

Make a new file called hello.php with your editor or IDE of choice, and type the following:

<?php declare(strict_types=1);

echo "Hello, world.\n";

Save the file, and go to your command line. Navigate to your PHP code folder, and run it by typing php hello.php. You should see:

$ php hello.php
Hello, world
$

Every PHP file should start with <?php declare(strict_types=1);. <?php tells the PHP interpreter that you're writing PHP, and strict_types tells PHP not to try to guess what you mean so much. Historically PHP has tended to be very loose, and prefer to make the best guess of what's required if it isn't clear instead of giving up. That's probably good for writing a website one page at a time, but for applications we need the computer to stop and tell us what's wrong if we make a mistake, not plough ahead and give us a wrong result.

echo simply outputs strings of text. We could use print, which is quicker to say, but we prefer echo, which is 20% shorter to write.