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Determine bytes needed to hold integer (Python3) (Python recipe) by teddy_k
ActiveState Code (http://code.activestate.com/recipes/578766/)

Convenience function to determine the number of bytes needed for a specified integer (split into multiple lines for clarity's sake ... could just as easily be a one-liner).

If this is already a defined function within Python, please let me know--a quick web search turned up nothing.

Python, 16 lines
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import math

def int_to_bytes_needed(integer):
    bytes_needed = math.pow((integer + 1),.125)/2
    rounded_bytes_to_whole = math.ceil(bytes_needed)
    return rounded_bytes_to_whole


# One-liner versoins:

# required_bytes = lambda x: ((((x+1)**.125)/2)//1)+1
# required_bytes(INTEGER_GOES_HERE)

# or:

# ((((INTEGER_GOES_HERE +1 )**.125)/2)//1) + 1
Tags: bytes, conversion, integer

2 comments

Paul Moore 10 years, 6 months ago  # | flag

From Python 3.1, integers have a bit_length() method:

>>> n = 12
>>> n.bit_length()
4

See http://docs.python.org/3.4/library/stdtypes.html#int.bit_length

teddy_k (author) 10 years, 6 months ago  # | flag

Thank you. That is precisely what I wanted.