Polymorphism in PHP is one of the important concepts in OOPs.
Polymorphism is a Greek word. Polymorphism is created by two different words poly (means many) and morph (means forms).
It is another functionality of OOPS. In a programming language, two types of Polymorphism are there.
- Function overriding (Run time Polymorphism)
- Function Overloading(Compile time Polymorphism)
Function Overriding in PHP
Overriding happens only in child class.
If the parent class declares a function and the child class wants to override the parent class function then function overriding means run time polymorphism happened.
Polymorphism example in PHP
Here are taking a simple example.
Created a class parent class it has a method name().
created another class child class it inherits the feature of the parent class.
child class has also the same method name().
Defining the same method in a child is known as method overriding.
name(); echo '
'; $arrobj = array(); $arrobj[0] = new parentclass; $arrobj[1] = new childclass; foreach ($arrobj as $key => $val) { echo $val->name(); echo "
"; } //It called child function instead of parent function ?>
Output
Calling show method of Shape Shape is no defined Calling show method of Circle Showing a Circle Calling show method of Rectangle Showing a Rectangle Calling show method of Square Showing a Square Calling show method of Triangle Showing a Triangle
Polymorphism example to call different methods in PHP
Here we have taken the example of Shapes.
The shape is a base class with a method shown ().
Child classes of Shape are Circle, Rectangle, Square, and Triangle.
all have an overridden method show().
';
}
}
class Circle {
function show() {
echo 'Showing a Circle
';
}
}
class Rectangle {
function show() {
echo 'Showing a Rectangle
';
}
}
class Square {
function show() {
echo 'Showing a Square
';
}
}
class Triangle {
function show() {
echo 'Showing a Triangle
';
}
}
//creating Shape object
$objShape = new Shape();
//calling Shape method with shape object
echo ' Calling show method of Shape
';
$objShape->show();
//creating Circle object
$objCircle = new Circle();
//calling Circle method with shape object
echo ' Calling show method of Circle';
$objCircle->show();
//creating Rectangle object
$objRectangle = new Rectangle();
//calling Rectangle method with shape object
echo ' Calling show method of Rectangle';
$objRectangle->show();
//creating Square object
$objSquare = new Square();
//calling Square method with shape object
echo ' Calling show method of Square';
$objSquare->show();
$objTriangle = new Triangle();
//calling show method with shape object
echo ' Calling show method of Triangle';
$objTriangle->show();
?>
Output
Calling show method of Shape Shape is no defined Calling show method of Circle Showing a Circle Calling show method of Rectangle Showing a Rectangle Calling show method of Square Showing a Square Calling show method of Triangle Showing a Triangle