What does & mean in python

Question

Hi I came across the following code

numdigits = len(cardNumber)
oddeven = numdigits & 1

what exactly is going on here? I\'m not sure wh

Answer 1

It's a bitwise operation, in this case assigning zero to oddeven if cardNumber has an even number of elements (and one otherwise).

As an example: suppose len(cardNumber) == 235. Then numdigits == 235, which is 0b11101011 in binary. Now 1 is '0b00000001' in binary, and when you "AND" them, bitwise, you'll get:

  11101011
  &
  00000001
  ----------
= 00000001

Similarly, if numdigits were 234, you would get:

  11101010
  &
  00000001
  ----------
= 00000000

So, it's basically a obfuscated way of checking if len(cardNumber) % 2. Probably written by someone with a C background, because it is not very pythonic - readability counts!