Accessing lower half of a 64bit integer

How can access the lower half of a 64bit integer using C or C++? I can do it easily in Assembly but I have no clue on how to do it in C/C++

EDIT: Wha开发者_如何学Got about accessing the upper half?

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long long BigOne = 0x1234567890ABCDEFLL;
long long LowerHalf = BigOne & 0xFFFFFFFFLL;
long long UpperHalf = (BigOne >> 32) & 0xFFFFFFFFLL;

Sorry if the hexadecimal literals require some prefix/suffix, I'm not very familiar with C. Please fix the answer if you know.

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I have used all kinds of tricks to do this before. Using unions, long shifts ect..

Nowadays I just use memcopy. It may sound inefficient, but last time I checked the compiler optimized the code quite nice:

int32_t higher32 (unsigned long long arg)
{
  unsigned char * data = (unsigned char *) arg;
  int32_t result;
  memcpy (&result, data+4, sizeof (int32_t));
  return result;
}

int32_t lower32 (unsigned long long arg)
{
  unsigned char * data = (unsigned char *) arg;
  int32_t result;
  memcpy (&result, data+0, sizeof (int32_t));
  return result;
}