How do I use bitwise operators on a “double” on C++?

Question

I was asked to get the internal binary representation of different types in C. My program currently works fine with \'int\' but I would like to use it with \"double\" and \"

Answer 1

Do a bit-wise cast of a pointer to the double to long long * and dereference. Example:

inline double bit_and_d(double* d, long long mask) {
  long long t = (*(long long*)d) & mask;
  return *(double*)&t;
}

Edit: This is almost certainly going to run afoul of gcc's enforcement of strict aliasing. Use one of the various workarounds for that. (memcpy, unions, __attribute__((__may_alias__)), etc)