C++ Code for Function Overriding Without virtual

Example

In C++, function overriding happens when a derived class defines a function with the same name as a base class function.

• Unless the base class method is specified as virtual, the compiler engages in early binding (compile-time decision).

• This implies that the base class version will be invoked even when the pointer points to an object of the derived classes.
• This leads to a lack of real-time polymorphism occurring.

---

Code Example

#include <iostream>
using namespace std;
class Animal {
public:
    void sound() {   // Not virtual
        cout << "Animal makes a sound" << endl;
    }
};
class Dog : public Animal {
public:
    void sound() {
        cout << "Dog barks" << endl;
    }
};
int main() {
    Animal* a1;
    Dog d;
    a1 = &d;

    a1->sound();   // Calls Animal's version (not Dog's)
    return 0;
}

---

Output

Animal makes a sound

Short Explanation

• In this instance, Dog suppresses the method sound.

• But since sound() in Animal is not virtual, the call a1->sound() is resolved at compile time.

• Therefore, the base version (Animal makes a sound) is run.

• In order to implement runtime polymorphism and have it print out Dog barks, we need to declare a base class method as virtual.

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