copy_cast.cpp

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

template<typename From, typename To>
inline To copy_cast(const From& from)
{
  To to;
  memcpy(&to, &from, sizeof(from));
  return to;
}

float one() {
  return floorf((float)rand() / RAND_MAX) + 1.0f; // Always returns 1.0f
}

int main() {
#ifdef COPY_CAST
  float f = one();
  register int* fbits = copy_cast<float*, int*>(&f);
  f += one();
  printf("original: %d alias: %d floating: %f\n", *copy_cast<float*, int*>(&f), *fbits, f);
#else
  float f = one();
  register int* fbits = (int*)(&f);
  f += one();
  printf("original: %d alias: %d floating: %f\n", *((int*)&f), *fbits, f);
#endif
  return 0;
}