Why is Math.floor() used instead of integer division in BER Codec

Question

I am looking at the SNMPBEECodec which can be seen at this location
In particular I am looking at the function encodeLength()
A snippet I am interested in

        int numBytes = 0;
        int temp = length;
        while (temp > 0)
        {
            ++numBytes;
            temp = (int)Math.floor(temp / 256);
        }   

(from the Drexel SNMP library).

I would like to know why Math.floor() is used instead of just a simple integer division like temp/256. It seems the simple integer division would give the same result. Or is there a technical difference?

Answer 1

To answer the technical part of your question:

Using math.floor() is superfluous: temp / 256 is an integer (by Java's rules for integer arithmetic), and using Math.floor() on an integer is pointless. You could simply use temp / 256.

Why the author did this is impossible to answer without reading their mind. The author might simply have been confused about the behaviour of division in Java, and decided to "play it safe" - but that is just speculation.

Answer 2

Well, unfortunately the author can no longer read his mind either - it's been about 12 years since I wrote this, so I forget the reason I didn't just use integer division. Some thoughts: I use integer division elsewhere assuming the usual behavior, so it wouldn't likely have been basic confusion on the rules for integer division in Java; it's possible (though unlikely) that I was at some point using a non-integral data type for the argument, and didn't get rid of the superfluous floor() when I changed; or perhaps (more likely) I was at some point attempting to round up rather than down while developing the algorithm, using ceil() as a cheap (= fewer characters) way to do this, and just reflexively switched to floor() when I changed.

So unfortunately the real reason is lost in the mists of time... but I agree, the floor() is superfluous. I should really post the code on Github or the like so folks can improve and evolve it. \ Jon