Is it possible to do bitwise operations on a string in Python?

Question

This fails, not surprisingly:

>>> 'abc' << 8
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for <<: 'str' and 'int'
>>> 

With ascii abc being equal to 011000010110001001100011 or 6382179, is there a way to shift it some arbitrary amount so 'abc' << 8 would be 01100001011000100110001100000000?

What about other bitwise operations? 'abc' & 63 = 100011 etc?

Answer 1

What you probably want is the bitstring module (see http://code.google.com/p/python-bitstring/). It seems to support bitwise operations as well as a bunch of other manipulations of bit arrays. But you should be careful to feed bytes into it (e.g. b'abc' or bytes('abc')), not characters - characters can contain Unicode and occupy more than one byte.

Answer 2

It doesn't make any sense to do bitwise operations on strings. You probably want to use the struct module to convert your strings to numbers:

>>> import struct
>>> x = 'abc'
>>> x = '\x00' * (4-len(x)) + x
>>> number = struct.unpack('!i', x)[0]
>>> number
6382179

You can then do all your operations on number. When (if) you want a string back, you can do struct.pack('!i', number).