Inheritance

Overview

Inheritance allows a new class (derived) to inherit properties and behaviors from an existing class (base). This promotes massive code reuse. C++ supports various inheritance architectures.

Syntax

cpp

class Animal { /* Base */ };

// 1. Single
class Dog : public Animal {};

// 2. Multilevel
class Puppy : public Dog {};

// 3. Multiple
class Bird { /* Base 2 */ };
class FlyingDog : public Animal, public Bird {}; // Inherits from both

Common Pitfalls

Abusing inheritance when 'Composition' (a 'has-a' relationship) would be better than Inheritance (an 'is-a' relationship).

Interview Tips

Explain the 'Diamond Problem'. If Class B and C inherit from A, and Class D inherits from B and C, D gets TWO copies of A. This is solved using 'virtual inheritance' (`class B : virtual public A`).

Real-World Example

Basic Single Inheritance for a game character.

example

cpp

#include <iostream>
using namespace std;

// Base class
class Entity {
public:
    int x = 0, y = 0;
    void move() { cout << "Moving...\n"; }
};

// Derived class
class Player : public Entity {
public:
    void attack() { cout << "Attacking!\n"; }
};

int main() {
    Player p;
    p.move();   // Inherited
    p.attack(); // Specific to Player
    return 0;
}

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