What is abstract class in php?

In PHP, an abstract class is a class that cannot be instantiated on its own and is meant to be subclassed by other classes. Abstract classes can have abstract methods, which are declared but not implemented in the abstract class. Subclasses that extend an abstract class must provide concrete implementations for all abstract methods. Here are the key features of abstract classes in PHP: Cannot be Instantiated: An abstract class cannot be instantiated directly. It serves as a blueprint for other classes. May Contain Abstract Methods: Abstract classes can declare abstract methods, which are methods without an implementation in the abstract class itself. May Contain Concrete Methods: Abstract classes can also have regular (concrete) methods with implementations. Designed for Inheritance: The primary purpose of abstract classes is to be extended by other classes. Subclasses inherit the structure (methods and properties) of the abstract class. Abstract Methods Must be Implemented: Any class that extends an abstract class must provide concrete implementations for all abstract methods declared in the abstract class. Here's an example of an abstract class in PHP: php abstract class Shape { abstract public function calculateArea(); // Abstract method without implementation public function displayArea() { echo "Area: " . $this->calculateArea() . PHP_EOL; } } class Circle extends Shape { private $radius; public function __construct($radius) { $this->radius = $radius; } public function calculateArea() { return pi() * pow($this->radius, 2); } } // Usage $circle = new Circle(5); $circle->displayArea(); In this example, Shape is an abstract class with an abstract method calculateArea(). The Circle class extends the Shape class and provides a concrete implementation for the calculateArea() method. The displayArea() method in the Shape class uses the abstract calculateArea() method to display the area of the shape. read less