ActionScript code to convert bytes to kb, mb, gb etc

Question

I have a utility function that will display a filesize in an appropriate form like Windows Explorer does, i.e; convert it to nearest KB, MB, GB etc. I wanted to know if the code that i wrote is correct, and if it can be made simpler.

The function that i wrote is as follows :

public static function formatFileSize(bytes:int):String
    {
        if(bytes < 1024)
            return bytes + " bytes";
        else
        {
            bytes /= 1024;
            if(bytes < 1024)
                return bytes + " Kb";
            else
            {
                bytes /= 1024;
                if(bytes < 1024)
                    return bytes + " Mb";
                else
                {
                    bytes /= 1024;
                    if(bytes < 1024)
                        return bytes + " Gb";
                }
            }
        }
        return String(bytes);
    }

While it does the job for me at the moment, i feel it could be written in an even simpler way and maybe even optimized.

thanks in advance

Workout

if you use the 'curly bracket' button on your code it'll format it like code instead of as a quote. – Landonlandor

you can use nested ? : operators instead of if(){}else{} – As

@flextras : thank you for correcting that. i was not aware of that yet :) – Workout

@As : that will end up getting more complex and cumbersome to manage. – Workout

The abbreviations in your code should be KiB, MiB, and GiB. See here. – Clein

Answer 1

Here's a simpler way of doing it:

private var _levels:Array = ['bytes', 'Kb', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];

private function bytesToString(bytes:Number):String
{
    var index:uint = Math.floor(Math.log(bytes)/Math.log(1024));
    return (bytes/Math.pow(1024, index)).toFixed(2) + this._levels[index];
}

I included it up to yottabytes for completeness :)

Kahlil

couldn't you just do something like var level:int = int(bytes/1024), then print out with return level + _levels[level]; with a catch for if it's less that 1Kb? – Trimester

@divillysausages, er no. Have you even tried your suggestion? With your 'calculation', you'd only get the kylobytes. Filesizes are exponention (number / 1024 / 1024 / 1024 / ...etc) – Kahlil

thank you J_A_X for the answer. its perfectly what i was looking for. – Workout

Answer 2

@J_A_X has the best way to do this, however for the future, I suggest returning early when you find you have nested if...else...if statements like you have.

public static function formatFileSize(bytes:int):String
{
    if(bytes < 1024)
        return bytes + " bytes";

    bytes /= 1024;
    if(bytes < 1024)
        return bytes + " Kb";

    bytes /= 1024;
    if(bytes < 1024)
        return bytes + " Mb";

    bytes /= 1024;
    if(bytes < 1024)
        return bytes + " Gb";

    return String(bytes);
}

Paschall

thank you jeremy. can't think how i missed writing this way and instead ended up with a nested if. it did seem weird for me. – Workout

hey, do you think a recursive approach could perform better in this case? – Workout

@silverback: No, because then you would have to keep track of how far deep so you can accurately display if it's KB or GB, etc. – Paschall