C++ - Sample usages of xxx_cast()

casts.cpp

#include <iostream>
using namespace std;

class Base {
    virtual void f() {};
};

class Derived: public Base {
};

int main(int argc, const char *argv[])
{
    // dynamic_cast
    {
        Base *bp, b;
        Derived *dp, d;

        cout << endl;
        cout << "== dynamic_cast" << endl;

        bp = &b;
        if (dp = dynamic_cast<Derived *> (bp)) {
            cout << "cast bp(&b) to dp: success" << endl;
        } else {
            cout << "cast bp(&b) to dp: failure" << endl;
        }

        bp = &d;
        if (dp = dynamic_cast<Derived *> (bp)) {
            cout << "cast bp(&d) to dp: success" << endl;
        } else {
            cout << "cast bp(&d) to dp: failure" << endl;
        }
    }

    // const_cast
    {
        int i = 10;
        const int *p = &i;
        int *q;

        cout << endl;
        cout << "== const_cast" << endl;

        //*p = 20;
        //-> error

        q = const_cast<int *> (p);
        *q = 20;

        cout << "*p = " << *p << endl;
    }

    // reinterpret_cast
    {
        int i;
        char *p = "hello";

        cout << endl;
        cout << "== dynamic_cast" << endl;

        i = reinterpret_cast<int> (p);
        //-> warning: deprecated conversion from string constant to ‘char*’

        cout << "i = " << i << endl;
    }

    // static_cast
    {
        float f = 3.14;
        int i;

        cout << endl;
        cout << "== static_cast" << endl;

        i = static_cast<int> (f);
        cout << "i = " << i << endl;
    }

    return 0;
}

// vim: filetype=cpp