Calculate size of a file

Calculate size

### Calculate size
function _format_bytes($a_bytes)
{
    if ($a_bytes < 1024) {
        return $a_bytes . ' B';
    } elseif ($a_bytes < 1048576) {
        return round($a_bytes / 1024, 2) . ' KB';
    } elseif ($a_bytes < 1073741824) {
        return round($a_bytes / 1048576, 2) . ' MB';
    } elseif ($a_bytes < 1099511627776) {
        return round($a_bytes / 1073741824, 2) . ' GB';
    } elseif ($a_bytes < 1125899906842624) {
        return round($a_bytes / 1099511627776, 2) . ' TB';
    } elseif ($a_bytes < 1152921504606846976) {
        return round($a_bytes / 1125899906842624, 2) . ' PB';
    } elseif ($a_bytes < 1180591620717411303424) {
        return round($a_bytes / 1152921504606846976, 2) . ' EB';
    } elseif ($a_bytes < 1208925819614629174706176) {
        return round($a_bytes / 1180591620717411303424, 2) . ' ZB';
    } else {
        return round($a_bytes / 1208925819614629174706176, 2) . ' YB';
    }
}

### Usage: _format_bytes(filesize($file)