#include <iostream>   //C++ example
#include <cstdlib>
#include <cmath>      //for sqrt
using namespace std;

int main()
{
	double (*const p)(double) = sqrt;

	cout << "p == "
		<< reinterpret_cast<void *>(reinterpret_cast<size_t>(p)) << "\n"
		<< "sqrt == "
		<< reinterpret_cast<void *>(
		   reinterpret_cast<size_t>(
		   static_cast<double (*)(double)>(sqrt)))
		<< "\n\n";

	double d = (*p)(2.0);
	cout << "d == " << d << "\n"
		<< "sqrt(2.0) == " << (*p)(2.0) << "\n\n";

	d = p(2.0);
	cout << "d == " << d << "\n"
		<< "sqrt(2.0) == " << p(2.0) << "\n";

	return EXIT_SUCCESS;
}