1.dynamic_cast <new_type> (expression)
2.reinterpret_cast <new_type> (expression)
3.static_cast <new_type> (expression)
4.const_cast <new_type> (expression)

#include <iostream>
#include <boostpolymorphic_cast.hpp>

class Base{
    public: virtual ~Base() = default;
};

class D1 : public Base{
    public: virtual ~D1() = default;
};

class D2 : public Base{
    public: virtual ~D2() = default;
};


int main(void)
{
    D1 d1;
    Base* b = &d1;
    Base* b2 = nullptr;

    std::cout << "n---Testing valid cast---n";
    std::cout << "cast from base to d1: " << boost::polymorphic_cast<D1*>(b) << "n";

    try
    {
        std::cout << "n---Testing invalid cast---n";
        std::cout << "base to d2: " << boost::polymorphic_cast<D2*>(b) << "n";
    }
    catch (...)
    {
        std::cout << "cast from based to d2 failedn";
    }

    try
    {
        std::cout << "n---Testing nullptr cast---n";
        std::cout << "null to d1: " << boost::polymorphic_cast<D1*>(b2) << "n";
    }
    catch (...)
    {
        std::cout << "cast from null to d1 failedn";
    }
}

---Testing valid cast---
cast from base to d1: 00AFFBD4

---Testing invalid cast---
cast from based to d2 failed

---Testing nullptr cast---
cast from null to d1 failed