A Class is a blueprint for creating objects. It contains data members (variables) and member functions (methods). An Object is an instance of a class.

Use classes to model real-world entities, encapsulate data, and implement complex systems in a modular way.

• Object Creation: $O(1)$ (depends on constructor logic).
• Member Access: $O(1)$.

cpp Standard
class Car {
public:
    string brand;
    void drive() {
        std::cout << "Driving " << brand << endl;
    }
};

int main() {
    Car myCar;
    myCar.brand = "Tesla";
    myCar.drive();
}

• Forgetting the ; at the end of a class definition.
• Accessing private members directly from outside the class.
• Not defining a constructor, leading to uninitialized data members.