Write large 4 byte integer as an unsigned, binary

Question

I have integers which floats between values: 4000000000-4294967000 (which is less than int max for a 4 byte unsigned int)

and i want to save it to file, and then re-read value

$f = fopen($fileName, 'wb'); fwrite($f, pack('I', $value));

It is important that in file, value must be exact 4 byte unsigned int, because external devices will expect that format of data. But PHP stores that big values as float, and destroys binary representation.

How i can write that numbers to file in that format?

[EDIT] @FractalizeR thx this works i have:

protected static function handleUint($direction, $value)
{
    if($direction == 'encode')
    {
        $first2bytes    = intval($value / (256 * 256));
        $second2bytes   = intval($value - $first2bytes);

        return pack('n2', $first2bytes, $second2bytes);
    }
    else
    {
        $arr = unpack('n2ints', $value);
        $value = $arr['ints1'] * (256 * 256) + intval($arr['ints2']) - 1;
        return $value;
    }
}

But i dont quite understand, why i have to -1 on the returning value, and is this binary will be produced correct?

Answer 1

Well, split that 4 bytes number into 2 2-bytes numbers (integer divide by 256*256 to get the first word and subtract that value from original one to get the second one) and write in two packs.