Python: manipulating bits in a char in a string

Question

I know how to read bits inside an int in Python but not how to do so on a char. For an int, this elementary operation works: a & (2**bit_index) . But for a single character it gives the following error message: unsupported operand type(s) for &: 'str' and 'int'

In case, this "subtlety' matters, I'm also reading my char from a string object using:

for my_char in my_string:

I'm stressing this point, because it could be that my_char is actually a string of length one and not a char, just because I know really little about python handle of types.

Thank you.

Answer 1

Try this instead: ord(a) & (2**bit_index).

In python there is no separate character type, a character is simply a string of size one. So if you want to perform bit manipulations with string of size 1, you can use ord() to convert it to int.

Answer 2

You can use a bytearray instead of a string. The individual elements are integers, but you can still do basic string manipulation on the whole:

>>> arr = bytearray('foo')
>>> type(arr[0])
<type 'int'>
>>> arr.replace('o', 'u')
bytearray(b'fuu')

Answer 3

Correct -- it is a string of length 1 and not a char.

Convert your string to a list of integers:

>>> s = "hello world"
>>> l = [ord(c) for c in s]

Then you can use bitwise operators on specific offsets:

>>> l[1] = l[1] << 1
>>> print "".join(chr(c) for c in l)
h?llo world

Answer 4

Python doesn't really have char type. You have a string of length one. You need to convert it to int before you can apply those operators in it. Depending on what is in my_string this might work: int(my_char, 10)