Install Phiki
composer require phiki/phiki:^2.0
Create a new Phiki instance
use Phiki\Phiki;
$phiki = new Phiki();
Highlight your code
use Phiki\Grammar\Grammar;
use Phiki\Theme\Theme;
$code = file_get_contents('path/to/your/code.php');
$highlighted = $phiki->codeToHtml($code, Grammar::Php, Theme::GithubLight);
echo $highlighted;