PHP class hierarchy for library system

PHP OOP: Exercise-6 with Solution

Write a PHP a class hierarchy for a library system, including classes like 'LibraryItem', 'Book', 'DVD', etc. Implement appropriate properties and methods for each class.

Sample Solution:

PHP Code :

<?php
 class LibraryItem {
    protected $title;
    protected $author;
    protected $year;

    public function __construct($title, $author, $year) {
        $this->title = $title;
        $this->author = $author;
        $this->year = $year;
    }

    public function getTitle() {
        return $this->title;
    }

    public function getAuthor() {
        return $this->author;
    }

    public function getYear() {
        return $this->year;
    }
}

class Book extends LibraryItem {
    protected $genre;

    public function __construct($title, $author, $year, $genre) {
        parent::__construct($title, $author, $year);
        $this->genre = $genre;
    }

    public function getGenre() {
        return $this->genre;
    }

    public function displayDetails() {
        echo "Title: " . $this->title . "</br>";
        echo "Author: " . $this->author . "</br>";
        echo "Year: " . $this->year . "</br>";
        echo "Genre: " . $this->genre . "</br>";
    }
}

class DVD extends LibraryItem {
    protected $duration;

    public function __construct($title, $author, $year, $duration) {
        parent::__construct($title, $author, $year);
        $this->duration = $duration;
    }

    public function getDuration() {
        return $this->duration;
    }

    public function displayDetails() {
        echo "</br>Title: " . $this->title . "</br>";
        echo "Author: " . $this->author . "</br>";
        echo "Year: " . $this->year . "</br>";
        echo "Duration: " . $this->duration . " minutes";
    }
}

$book = new Book("Don Quixote", "Miguel de Cervantes", 1605, "Epic novel");
$book->displayDetails();

$dvd = new DVD("The Land Before Time", "Charles Grosvenor", 2010, 150);
$dvd->displayDetails();
?>

Sample Output:

Title: Don Quixote
Author: Miguel de Cervantes
Year: 1605
Genre: Epic novel

Title: The Land Before Time
Author: Charles Grosvenor
Year: 2010
Duration: 150 minutes

Explanation:

In the above exercise -

• The "LibraryItem" class serves as the base class for all library items and defines common properties like $title, $author, and $year. It also provides getter methods to access these properties.
• The "Book" class extends the LibraryItem class and adds an additional property $genre. It has its own constructor to initialize the properties, and a getGenre() method to access the genre. It also overrides the displayDetails() method to display specific details of a book.
• The "DVD" class also extends the LibraryItem class and adds an additional property $duration. It has its own constructor and a getDuration() method to access the duration. It also overrides the displayDetails() method to display specific details of a DVD.

Flowchart:

PHP Code Editor:

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