Properties and visibility in PHP - Mini Project: Build & Apply

Properties and visibility

📖 Scenario: You are creating a simple PHP class to represent a Book in a library system. Each book has a title and an author. You want to control how these properties can be accessed and changed from outside the class.

🎯 Goal: Build a PHP class called Book with properties that have different visibility levels. Learn how to set and get these properties safely.

📋 What You'll Learn

Create a class named Book

Add a public property called title

Add a private property called author

Add a public method setAuthor to set the author property

Add a public method getAuthor to get the author property

Create an instance of Book and set the title and author

Print the title and author of the book

💡 Why This Matters

🌍 Real World

Controlling access to data inside objects is important in real-world software to protect sensitive information and keep code organized.

💼 Career

Understanding properties and visibility is a key skill for PHP developers working on web applications, APIs, and backend systems.

1

Create the Book class with a public title property

Create a class called Book with a public property named title and set it to an empty string.

PHP

<?php

// Create class Book with public property title
class Book {
    public string $title = "";
}

Need a hint?

Use public string $title = ""; inside the class to create the property.

2

Add a private author property

Inside the Book class, add a private property called author and set it to an empty string.

PHP

<?php

class Book {
    public string $title = "";
    // Add private property author
    private string $author = "";
}

Need a hint?

Use private string $author = ""; to keep the author hidden from outside.

3

Add public setter and getter methods for author

Add two public methods inside Book: setAuthor(string $name) to set the author property, and getAuthor() to return the author property.

PHP

<?php

class Book {
    public string $title = "";
    private string $author = "";

    // Add setAuthor method
    public function setAuthor(string $name) {
        // Your code here
    }

    // Add getAuthor method
    public function getAuthor(): string {
        // Your code here
    }
}

Need a hint?

Use $this->author = $name; inside setAuthor and return $this->author; inside getAuthor.

4

Create a Book instance, set properties, and print them

Create a new Book object called $myBook. Set its title to "1984" and use setAuthor to set the author to "George Orwell". Then print the title and author in the format: Title: 1984, Author: George Orwell.

PHP

author = $name;
    }

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

// Create Book instance and set properties
$myBook = new Book();
// Your code here

Need a hint?

Use $myBook->title = "1984"; and $myBook->setAuthor("George Orwell");. Then print with print("Title: {$myBook->title}, Author: {$myBook->getAuthor()}");.