---------------------------------------- > From: steve+comp.lang.pyt...@pearwood.info > Subject: Re: How to get an integer from a sequence of bytes > Date: Mon, 27 May 2013 15:00:39 +0000 > To: python-list@python.org > > On Mon, 27 May 2013 16:45:05 +0200, Mok-Kong Shen wrote: > >> From an int one can use to_bytes to get its individual bytes, but how >> can one reconstruct the int from the sequence of bytes? > > Here's one way: > > py> n = 11999102937234 > py> m = 0 > py> for b in n.to_bytes(6, 'big'): > ... m = 256*m + b > ... > py> m == n > True > > > -- > Steven > > -- > http://mail.python.org/mailman/listinfo/python-list
Python 2 doesn't have to_bytes()! :( # Python 2, LSB 1st def to_lil_bytes(x): r = [] while x != 0: r.append(int(x & 0b11111111)) x>>= 8 return r # Python 2, LSB 1st def from_lil_bytes(l): x = 0 for i in range(len(l)-1, -1, -1): x <<= 8 x |= l[i] return x # Python 2, MSB 1st def to_big_bytes(x): r = [] while x != 0: r.insert(0, int(x & 0b11111111)) x>>= 8 return r # Python 2, MSB 1st def from_big_bytes(l): x = 0 for i in range(len(l)): x <<= 8 x |= l[i] return x Can it be faster? -- http://mail.python.org/mailman/listinfo/python-list
