What is the difference between an interface and an abstract class

An interface and an abstract class are both tools in object-oriented programming that allow you to define methods that must be implemented in derived classes. However, they serve different purposes and have distinct characteristics.

Key Differences

Definition: An interface is a contract that defines a set of methods without implementing them, while an abstract class can have both fully implemented methods and abstract methods.
Multiple Inheritance: A class can implement multiple interfaces but can inherit from only one abstract class.
Access Modifiers: Methods in an interface are implicitly public and cannot be private or protected. In contrast, an abstract class can have methods with any access modifier.
State Management: Abstract classes can have member variables and maintain state, while interfaces cannot hold any state.

Example


        // Defining an interface
        interface Vehicle {
            public function start();
            public function stop();
        }
        
        // Defining an abstract class
        abstract class Car {
            protected $color;

            public function __construct($color) {
                $this->color = $color;
            }

            abstract public function drive();

            public function getColor() {
                return $this->color;
            }
        }

        // Implementing the interface
        class Tesla extends Car implements Vehicle {
            public function start() {
                echo "Tesla starting...\n";
            }

            public function stop() {
                echo "Tesla stopping...\n";
            }

            public function drive() {
                echo "Driving a {$this->color} Tesla!\n";
            }
        }

What is the difference between an interface and an abstract class

Key Differences

Example

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What is the difference between an interface and an abstract class

Key Differences

Example

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