activate RTTI in c++

Question

Can anybody tell me how to activate RTTI in c++ when working on unix. I heard that it can be disabled and enabled. on my unix environment,how could i check whether RTTI is e

Answer 1

Enabling and disabling RTTI must be a compiler specific setting. In order for the dynamic_cast<> operation, the typeid operator or exceptions to work in C++, RTTI must be enabled. If you can get the following code compiled, then you already have RTTI enabled (which most compilers including g++ do automatically):

#include 
#include 

class A
{
public:
  virtual ~A () { }
};

class B : public A
{
};

void rtti_test (A& a)
{
  try
    {
      B& b = dynamic_cast (a);
    } 
  catch (std::bad_cast)
    {
      std::cout << "Invalid cast.\n";
    }
  std::cout << "rtti is enabled in this compiler.\n";
}

int
main ()
{
  A *a1 = new B;
  rtti_test (*a1);  //valid cast
  A *a2 = new A;
  rtti_test (*a2);  //invalid cast
  return 0;
}