Smart pointer example with mis-use of bool conversion

smart_ptr_bad_bool_conversion.cpp

// Interesting issue about conversion operators in C++
//http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1592.pdf

#include <iostream>

template <class T>
class Ptr
{
    // stuff
public:
    operator bool() const
    {
        if( rawptr_ )
            return true;
        else
            return false;
    }
private:
    T * rawptr_;
};

int main()
{
    Ptr<int> p1;
    Ptr<float> p2;
    std::cout << "p1 + p2 = " << p1 + p2 << std::endl; // prints 0, 1, or 2
    return 0;
}