CODEWITHSUNDEEP
php
The Humble Rat
The Humble Rat

Reputation: 4696

Convert Gigabytes to Bytes

I am in the position where I am trying to convert gigabytes to bytes from a submit form. I have searched around and I am unable to find anything suitable. Currently when converting bytes to gigabytes I use this method, which works perfectly.

public function byteFormat($bytes, $unit = "", $decimals = 2) 
{
    $units = array('B' => 0, 'KB' => 1, 'MB' => 2, 'GB' => 3, 'TB' => 4,
    'PB' => 5, 'EB' => 6, 'ZB' => 7, 'YB' => 8);

    $value = 0;
    if ($bytes > 0) {
    // Generate automatic prefix by bytes
    // If wrong prefix given
    if (!array_key_exists($unit, $units)) {
    $pow = floor(log($bytes)/log(1024));
    $unit = array_search($pow, $units);
    }

    // Calculate byte value by prefix
    $value = ($bytes/pow(1024,floor($units[$unit])));
    }

    // If decimals is not numeric or decimals is less than 0
    // then set default value
    if (!is_numeric($decimals) || $decimals < 0) {
    $decimals = 2;
    }

    // Format output
    return sprintf('%.' . $decimals . 'f '.$unit, $value);
}

There seems to be plenty of examples of bytes to other formats but not the other way around.

I have seen that I can convert the number 1.5 like so

round(($number[0] * 1073741824));

The result is 12992276070, however, when using the byteformat method shown above, I get the following 1610612736, this seems quite a difference between the two methods. Can anyone suggest a more stable method for converting gigabytes to bytes.

Upvotes: 0

Views: 582

Answers (3)

Gangnus
Gangnus

Reputation: 24464

numberOfBytes = round (numberOfGb * 1073741824)

is the exact answer to your question. It seems, you have miscalculated. Try to check it on a calculator.

The other problem is that if you have the source number of 2 digits, it is incorrect to give an answer in more or less than 2 digits. The correct counting will be:

source: 1.5GB
counting: 1.5GB*1073741824 B/GB= 1610612736 B
rounding to the last significant digit: 1610612736 B ~= 1.6e9 B
answer: 1.6e9 B

But, of course, many clients do not really want the correct answer, they want THEIR answer. It is up to you to choose.

Upvotes: 0

JoeC
JoeC

Reputation: 36

You can only get as accurate of a conversion as there are numbers after the decimal place. If you start with 1.29634 gigs you'll get a closer representation to it's actual byte value versus calling it 1.3 Gigs. Is that what you're after?

Upvotes: 0

user4587108
user4587108

Reputation:

Well there are two different unit symbol, decimal and binary. As you can see here, decimal multiplication is by 1000 and binary by 1024. so if you are using "B"(byte), just do something like:

$bytenumber=$giga*pow(1024,3);

if using "b"(bit) :

$bitnumber=$giga*pow(1000,3);

P.S:$giga is your giga number.

Upvotes: 1

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