How to store a 64 bit integer in two 32 bit integers and convert back again

Question

I\'m pretty sure its just a matter of some bitwise operations, I\'m just not entirely sure of exactly what I should be doing, and all searches return back \"64 bit vs 32 bit

Answer 1

Use a union and get rid of the bit-operations:

 // for int32_t, int64_t

union {
  int64_t big;
  struct {
    int32_t x;
    int32_t y;
  };
};
assert(&y == &x + sizeof(x));

simple as that. big consists of both x and y.