/**

* http://www.cplusplus.com/doc/tutorial/typecasting/

*/

#include <iostream>

using namespace std;

class A {

public:

int a;

virtual void dummp() {} // first mistake, virtual function is necessary for polymorphic

};

class B : public A { // second mistake inherit public

int b;

};

/*

int a = 7;

double* p1 = (double*) &a; // ok (but a is not a double)

double* p2 = static_cast<double*>(&a); // error

double* p2 = reinterpret_cast<double*>(&a); // ok: I really mean it

const int c = 7;

int* q1 = &c; // error

int* q2 = (int*)&c; // ok (but *q2=2; is still invalid code and may fail)

int* q3 = static_cast<int*>(&c); // error: static_cast doesn't cast away const

int* q4 = const_cast<int*>(&c); // I really mean it

*/

int main() {

A a;

B b;

try {

A *a = new A;

A *b = new B;

// if no virtual function defined in A

// error: cannot dynamic_cast ‘a’ (of type ‘class A*’) to type

// ‘class B*’ (source type is not polymorphic)

B *c;

c = dynamic_cast<B*>(a); // run time check to make sure completeness of object

if (!c) cout << "null pointer on a->c" << endl;

c = dynamic_cast<B*>(b);

if (!c) cout << "null pointer on b->c" << endl;

else cout << "succeed in casting b->c" << endl;

}

catch (exception& e) {

cout << "Exception: " << e.what();

}

return 1;

}