const int    INT_NULL           =    INT_MIN;
const int64  INT64_NULL         =    INT64_MIN;

constexpr double DOUBLE_NULL    =    -std::numeric_limits<double>::infinity();
constexpr float FLOAT_NULL      =    -std::numeric_limits<float>::infinity();

class Nuller {
public:
	operator int() const                { return INT_NULL; }
	operator int64() const              { return INT64_NULL; }
	operator double() const             { return DOUBLE_NULL; }
	operator float() const              { return FLOAT_NULL; }
	operator bool() const               { return false; }

	Nuller() {}
};

extern const Nuller Null;

template <class T> void SetNull(T& x) { x = Null; }

template <class T> bool IsNull(const T& x)       { return x.IsNullInstance(); }

template<> inline bool  IsNull(const int& i)     { return i == INT_NULL; }
template<> inline bool  IsNull(const int64& i)   { return i == INT64_NULL; }
template<> inline bool  IsNull(const double& r)  { return !(std::abs(r) < std::numeric_limits<double>::infinity()); }
template<> inline bool  IsNull(const float& r)   { return !(std::abs(r) < std::numeric_limits<float>::infinity()); }
template<> inline bool  IsNull(const bool& r  )  { return false; }

CONSOLE_APP_MAIN{
	double d=Null;
	float f=Null;
	double a=f;
	float b=d;
	Cout() << "d = " << d << "\n";
	Cout() << "f = " << f << "\n";
	Cout() << "a = " << a << "\n";
	Cout() << "b = " << b << "\n";
	Cout() << "a == f : " << (bool)(a==f) << "\n";
	Cout() << "b == d : " << (bool)(b==d) << "\n";
	Cout() << "IsNull(d) = " << IsNull(d) << "\n";
	Cout() << "IsNull(f) = " << IsNull(f) << "\n";
	Cout() << "IsNull(a) = " << IsNull(a) << "\n";
	Cout() << "IsNull(b) = " << IsNull(b) << "\n";
}