Overriding and the override Keyword

A derived class may override a base member function — but only if the signatures match exactly, and the base must say the function may be overridden (virtual, next lesson). Overriding is not overloading.

#include <iostream>
#include <string>

class Animal {
public:
    virtual ~Animal() = default;
    virtual void speak() const { std::cout << "...\n"; }
};

class Dog : public Animal {
public:
    void speak() const override { std::cout << "Woof\n"; }  // overrides
    void speak(int times) const;                             // would OVERLOAD, not override
};

class Cat : public Animal {
public:
    void speak() const override { std::cout << "Meow\n"; }
};

override: write it, always

override asks the compiler to verify a function really overrides something. Without it, a typo or a const mismatch silently creates a new function:

class Bird : public Animal {
public:
    void Speak() const override;   // compile error: no such base function (typo caught!)
    void speak() /* missing override + missing const */;   // new function, silent bug
};

The matching checklist

Same name, same parameter types, same const-qualification, compatible return type. override checks all of it for you at compile time — the keyword costs nothing and removes an entire class of quiet bugs.