Book.php

<?php

class Book
{
    private $title;
    
    function __construct(string $title_in)
    {
        $this->title = $title_in;
    }
    
    function getTitle(): string
    {
        return $this->title;
    }
    
    public function formatTitle(string $format): string
    {
        switch ($format) {
            case "uppercase":
                return strtoupper($this->getTitle());

            case "lowercase":
                return strtolower($this->getTitle());
                
            case "lcfirst":
                return lcfirst($this->getTitle());
                
            case "ucwords":
                return ucwords($this->getTitle());
                
            default:
                return $this->getTitle();
        }
    }
}