What is object slicing in C++ and how to avoid it?

Hello! I recently started learning C++ and encountered a problem that I can't understand. I have a base class `Animal` and a derived class `Dog` that adds a `breed` field. I wrote a function that takes `Animal` by value. When I pass a `Dog` object to it, the compiler doesn't give an error, but in the function I lose the breed data (the `breed` field). Here's my code: ```cpp #include #include class Animal { public: Animal(const std::string& name) : name_(name) {} virtual void speak() const { std::cout << "Animal sound\n"; } std::string getName() const { return name_; } private: std::string name_; }; class Dog : public Animal { public: Dog(const std::string& name, const std::string& breed) : Animal(name), bre