Python int -> binary?

Question

Am I reading this right?

There aren't any canned Python methods to convert an Integer (or Long) into a binary string in Python?

There are a myriad of dec2bin() functions out on Google... But I was hoping I could use a built-in function / library.

Answer 1

Unless I'm misunderstanding what you mean by binary string I think the module you are looking for is struct

Answer 2

Python's string format method can take a format spec:

>>> "{0:b}".format(10)
'1010'

Answer 3

If you're looking for bin() as an equivalent to hex(), it was added in python 2.6.

Answer 4

No language or library will give its user base everything that they desire (although Boost may claim to :-). You should be collecting snippets of code as you develop to ensure you never have to write the same thing twice.

Such as:

def bin(i):
    if i = 0:
        return "0"
    s = ''
    while i:
        if i & 1 == 1:
            s = "1" + s
        else:
            s = "0" + s
        i = i >> 1
    return s

which will construct your binary string based on the decimal value.

The idea is to use code from (in order of preference):

• the language.
• the libraries.
• third-party libraries with suitable licenses.
• your own collection.
• something new you need to write (and save in your collection for later).