Python: Converting from binary to String

Question

In Python, I have been able to take in a string of 32 bits, and convert this into a binary number with the following code:

def doConvert(string):
 binary = 0
 for letter in string:
 binary <<= 8
 binary += ord(letter)
 return binary

So for the string, 'abcd', this method will return the correct value of 1633837924, however I cannot figure out how to do the opposite; take in a 32 bit binary number and convert this to a string.

If someone could help, I would appreciate the help!

• andrewvincent7: @shuttle87 I'm using Python2
• shuttle87: Is it always a 32bit integer?
• andrewvincent7: yeah always a 32bit string being converted.

Answer 1

If you are always dealing with a 32 bit integer you can use the struct module to do this:

>>> import struct
>>> struct.pack(">I", 1633837924)
'abcd'

Just make sure that you are using the same endianness to both pack and unpack otherwise you will get results that are in the wrong order, for example:

>>> struct.pack("<I", 1633837924)
'dcba'

• andrewvincent7: Thanks, this works really well! What does the argument, ">I" do? I can't find a reasonable explanation in the docs.
• shuttle87: The I says that it is an unsigned integer. The > says that it is in big-endian format.
• Ayush: >>> help(struct) The optional first format char indicates byte order, size and alignment: @: native order, size & alignment (default) =: native order, std. size & alignment <: little-endian, std. size & alignment >: big-endian, std. size & alignment !: same as >
• shuttle87: help(struct) is a good idea! Also the struct documentation has a table with the possible formats.