PHP inheritance and polymorphism: revealing the essence of object-oriented programming

php editor Xiaoxin will take you to deeply explore the core of object-oriented programming-PHP inheritance and polymorphism. Mastering these two concepts will greatly improve the flexibility and reusability of your code, making your program more efficient and easier to maintain. This article will analyze the principles of inheritance and polymorphism for you and help you better understand and apply the essence of object-oriented programming.

inherit

Inheritance refers to the ability of one class (called a subclass) to obtain properties and methods from another class (called a parent class). Subclasses can reuse the code of the parent class and add new properties and methods of their own. Doing so reduces code duplication and makes the code easier to maintain.

The following is a simple example demonstrating inheritance:

class ParentClass {
public $name;

public function getName() {
return $this->name;
}
}

class ChildClass extends ParentClass {
public $age;

public function getAge() {
return $this->age;
}
}

$child = new ChildClass();
$child->name = "John Doe";
$child->age = 30;

echo $child->getName(); // "John Doe"
echo $child->getAge(); // 30

In this example, ChildClass inherits the name property and getName() method from ParentClass. ChildClass also adds its own age property and getAge() method.

Polymorphism

Polymorphism means that when a subclass object is used as a parent class object, the method will be called according to the method implementation of the subclass object. This is useful for writing scalable and flexible code, as you can create a parent class object and populate it with different child class objects without modifying the parent class code.

The following is a simple example demonstrating polymorphism:

class Animal {
public function makeSound() {
echo "Animal sound";
}
}

class Dog extends Animal {
public function makeSound() {
echo "Woof!";
}
}

class Cat extends Animal {
public function makeSound() {
echo "Meow!";
}
}

$animals = array(new Dog(), new Cat());

foreach ($animals as $animal) {
$animal->makeSound();
}

In this example, both the Dog and Cat classes inherit the makeSound() method from the Animal class. However, the Dog and Cat classes each override the makeSound() method so that when the method is called, it makes a different sound. When we use foreach to loop through the $animals array, the makeSound() method will be based on the subclass object used to fill the array. Different sounds.

Conclusion

Inheritance and polymorphism are the two basic concepts of OOP in PHP. Inheritance allows the creation of class hierarchies and allows subclasses to reuse the code of the parent class. Polymorphism allows creating a parent class object and populating it with different child class objects without modifying the parent class code. These concepts are useful for writing code that is scalable, flexible, and easy to maintain.

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