// The compilable parts of the program from above.

#include <iostream>
#include <cassert>
#include <cstdint>  // because of uintptr_t

int main(){
  using namespace std;

  // Casting between pointer and unsinged integers.
  int i;
  uintptr_t i_adr = reinterpret_cast<uintptr_t>(&i);     // Casting the address of i to an an unsigned int
  cout << i_adr << endl << endl;
  int *j = reinterpret_cast<int*>(i_adr);                // Casting the integer back to a pointer.
  assert(j == &i);                                       // The roundtrip must succeed.


  // Doing the trick (double to long long int) via pointers:
  static_assert(sizeof(long long int) == 
                sizeof(double), 
                "unexpected sizes");                     // Asserts statically that both types are of same byte length

  double e{124.567};
  double *pe{&e};                          
  long long int *llip
     {reinterpret_cast<long long int*>(pe)};             // OK (or at least done).
  std::cout << *llip << std::endl;                       // 4638466040292848959
}