C++ Polymorphism: from parent class to child [duplicate]

Answer 1

Above answers are good, conceptually you can think like this,

Your Car object which is derived from Vehicle class. You can refer Car as Vehicle, and can convert to Car as it originally belonged to Car. But it will be a problem if your Vehicle object actually representing Bike and trying to convert to Car. Thats why you need safe casting.

class Vehicle
{
    ...
};

class Car : public Vehicle
{
     ...
};

class Bike : public Vehicle
{
     ...
};


int main(int argc, char const *argv[])
{
     Vehicle* vehicle = new Car();
     Car* old_car = dynamic_cast(vehicle); 
     if(old_car) {
         // OK Vehicle is Car, use it
     }

     vehicle = new Bike();
     old_car = dynamic_cast(vehicle); 
     if(old_car) {
         // No Vehicle isn't Car, this code won't execute
     }

     return 0;
}