Question

To make this more clear, I’m going to put code samples:

$file = fopen('filename.ext', 'rb');

// Assume $pos has been declared
// method 1
fseek($file, $pos);
$parsed = fread($file, 2);

// method 2
while (!feof($file)) {
    $data = fread($file, 1000000);
}

$data = bin2hex($data);
$parsed = substr($data, $pos, 2);

$fclose($file);

There are about 40 fread() in method 1 (with maybe 15 fseek()) vs 1 fread() in method 2. The only thing I am wondering is if loading in 1000000 bytes is overkill when you’re really only extracting maybe 100 total bytes (all relatively close together in the middle of the file).

So which code is going to perform better? Which code makes more sense to use? A quick explanation would be greatly appreciated.

Answer 1

If you already know the offset you are looking for, fseek is the best method here, as there is no reason to load the whole file into memory if you only need a few bytes of it. The first method is better because you skip right to what you want in the file stream and read out a small portion. The second method requires you to read the entire file into memory, then seek through that while you could have just read it straight from the file. Hope this answers your question