[Claudio Grondi] > Let's consider a test source code given at the very end of this posting. > > The question is if Python allows somehow access to the bytes of the > representation of a long integer or integer in computers memory?
CPython does not expose its internal representation of longs at the Python level. > Or does Python hide such implementation details that deep, that there is > no way to get down to them? As above. > The test code below shows, that extracting bits from an integer value n > is faster when using n&0x01 than when using n%2 and I suppose it is > because %2 tries to handle the entire integer, It not only tries, it succeeds ;-) >where &0x01 processes only the last two bytes of it If x and y are positive longs, the time required to compute x&y in all recent CPythons is essentially proportional to the number of bits in min(x, y). > ... > If it were possible to 'tell' the %2 operation to operate only on one short of > the integer number representation there will be probably no difference in > speed. Is there a way to do this efficiently in Python like it is possible in > C when using pointers and recasting? No. > As I am on Python 2.4.2 and Microsoft Windows, I am interested in > details related to this Python version (to limit the scope of the > question). Doesn't really matter: same answers for all recent versions of CPython on all platforms. If you go back far enough, in older versions of CPython the time to compute x&y was proportional to the number of bits in max(x, y) (instead of min(x, y)). -- http://mail.python.org/mailman/listinfo/python-list
