Interested in making a PHP script that increments IP address from defined starting address to defined ending address

Question

I know I can do this easily by converting the IP addresses to decimal notation first using PHP built in functions like up2long and long2ip. I just want to be able to do the same using the standard IP address notation as an exercise.

The problem I am thinking goes like this: Given an starting IP address, say 192.168.1.100, and an ending IP address, say 201.130.22.10. Make the program that prints all the address numbers in that range (192.168.1.100, 192.168.1.101, … , 201.130.22.9, 201.130.22.10).

I was thinking that maybe the way to go would be to make a nested for loop inside a while condition until the first octet of the starting address matches the first octet of the ending address. Then execute the same block of code for the second octet and so on until the program reaches the ending address and finished.

I just started learning to program recently so it is quite possible that my of thinking and or writing code is far from elegant. If you were to this, how would you do it?

Answer 1

Something like this:

<?php

// works only for valid range
$start_ip = '10.0.0.1';
$end_ip = '10.0.20.1';

$start_arr = explode('.',$start_ip);
$end_arr = explode('.',$end_ip);

while($start_arr <= $end_arr)
{
    echo implode('.',$start_arr) . '<br>';

    $start_arr[3]++;
    if($start_arr[3] == 256)
    {
        $start_arr[3] = 0;
        $start_arr[2]++;
        if($start_arr[2] == 256)
        {
            $start_arr[2] = 0;
            $start_arr[1]++;
            if($start_arr[1] == 256)
            {
                $start_arr[1] = 0;
                $start_arr[0]++;
            }
        }
    }
}

?>

Answer 2

This is much less complicated:

<?php

// works only for valid range
$start_ip = ip2long('10.0.0.1');
$end_ip = ip2long('10.0.20.1');

while($start_ip <= $end_ip){
  echo long2ip($start_ip).'<br>';
  $start_ip++;
}

?>