🔴 Advanced · Lesson 24

Abstract Class vs Interface

Two Ways to Define a Contract

Both abstract classes and interfaces force child classes to implement certain methods, but they work differently.

Abstract Class

abstract class Shape {
    abstract public function area();   // no body
    public function describe() {        // can have real methods
        return "I am a shape";
    }
}
class Circle extends Shape {
    public function area() { return 3.14 * 5 * 5; }
}

Interface

interface Payable {
    public function pay();   // only signatures
}
class Order implements Payable {
    public function pay() { echo "Paid"; }
}

Difference

Abstract Class	Interface
can have real methods + properties	only method signatures
extends (one only)	implements (many allowed)

Summary

Abstract class: mix of real and abstract methods; single inheritance.
Interface: only signatures; a class can implement many.

Contract Define करने के दो तरीके

Abstract classes और interfaces दोनों child classes को कुछ methods implement करने पर मजबूर करते हैं, पर अलग तरह काम करते हैं।

Abstract Class

abstract class Shape {
    abstract public function area();   // no body
    public function describe() {        // real method भी हो सकती है
        return "I am a shape";
    }
}
class Circle extends Shape {
    public function area() { return 3.14 * 5 * 5; }
}

Interface

interface Payable {
    public function pay();   // सिर्फ signatures
}
class Order implements Payable {
    public function pay() { echo "Paid"; }
}

अंतर

Abstract Class	Interface
real methods + properties हो सकती हैं	सिर्फ method signatures
extends (सिर्फ एक)	implements (कई)

सारांश

Abstract class: real और abstract methods का मिश्रण; single inheritance।
Interface: सिर्फ signatures; class कई implement कर सकती है।

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