Count IP Addresses

  first    |    last     | ips_between
------------+-------------+-------------
 '10.0.0.0' | '10.0.0.50' |      50 
 '10.0.0.0' |  '10.0.1.0' |     256 
'20.0.0.10' |  '20.0.1.0' |     246

SELECT id, last::inet - first::inet as ips_between
FROM ip_addresses;

SELECT
DISTINCT id,
(d4+d3*256+d2*256*256+d1*256*256*256) as ips_between
FROM
(SELECT *,
cast(split_part(last,'.',1) as bigint) - cast(split_part(first,'.',1) as bigint) as d1,
cast(split_part(last,'.',2) as bigint) - cast(split_part(first,'.',2) as bigint) as d2,
cast(split_part(last,'.',3) as bigint) - cast(split_part(first,'.',3) as bigint) as d3,
cast(split_part(last,'.',4) as bigint) - cast(split_part(first,'.',4) as bigint) as d4
FROM ip_addresses) as ip;

SELECT id, 
       case when first::inet > last::inet 
            then first::inet - last::inet 
         else last::inet - first::inet 
       end as ips_between

FROM ip_addresses;

CREATE OR REPLACE FUNCTION ip_value(text) RETURNS bigint 
AS $$
DECLARE
  ip bigint[] := string_to_array($1, '.')::bigint[];
BEGIN
   RETURN (ip[1]*16777216 + ip[2]*65536 + ip[3]*256 + ip[4]);
END;
$$ LANGUAGE plpgsql;

SELECT id, ABS(ip_value(first) - ip_value(last)) AS ips_between
FROM ip_addresses

ELECT id
        ,((SPLIT_PART(last, '.',  1)::bigint - SPLIT_PART(first, '.',  1)::int)*256^3
        + (SPLIT_PART(last, '.',  2)::int    - SPLIT_PART(first, '.',  2)::int)*256^2
        + (SPLIT_PART(last, '.',  3)::int    - SPLIT_PART(first, '.',  3)::int)*256^1
        + (SPLIT_PART(last, '.',  4)::int    - SPLIT_PART(first, '.',  4)::int)*256^0)::bigint AS ips_between
  FROM ip_addresses;

public class CountIPAddresses {

  public static long ipsBetween(String start, String end) {
    String[] startArr = start.split("\\.");
    String[] endArr = end.split("\\.");
    long count = (Integer.parseInt(endArr[0]) - Integer.parseInt(startArr[0])) * 256 * 256 * 256;
    count += (Integer.parseInt(endArr[1]) - Integer.parseInt(startArr[1])) * 256 * 256 ;
    count += (Integer.parseInt(endArr[2]) - Integer.parseInt(startArr[2])) * 256 ;
    count += (Integer.parseInt(endArr[3]) - Integer.parseInt(startArr[3]));
    return count;
  }
}

public class CountIPAddresses {

  public static long ipsBetween(String start, String end) {
    return convertToLong(end) - convertToLong(start);
  }
  
  private static long convertToLong(String ip) {
    long res = 0;
    for (String s : ip.split("[.]") )
      res = res * 256 + Long.parseLong(s);
    return res;
  }
}

import java.util.Arrays;

public class CountIPAddresses {

    public static long ipsBetween(String start, String end) {
        long[] o = Arrays.stream(start.split("\\.")).mapToLong(Long::parseLong).toArray();
        long[] t = Arrays.stream(end.split("\\.")).mapToLong(Long::parseLong).toArray();

        long diff = 0;
        for (int i = 0; i < 4; i++) {
            diff += (t[i] - o[i]) << (8 * (3-i));
        }
        return diff;
    }
}

public class CountIPAddresses {

    public static long ipsBetween(String start, String end) {
        String[] s = start.split("\\."),
                 e = end.split("\\.");
        int v = 0;
        for (int i = 3 ; i >= 0 ; i--) v += (long) Math.pow(256.,3-i) * (Integer.parseInt(e[i]) - Integer.parseInt(s[i]));
        return v;
    }
}

public class CountIPAddresses {

  public static long ipsBetween(String start, String end) {
    String[] startNums = start.split("\\.");
    String[] endNums = end.split("\\.");
    
    long result = 0;
    
    result += (Long.valueOf(endNums[0]) - Long.valueOf(startNums[0]))*256*256*256;
    result += (Long.valueOf(endNums[1]) - Long.valueOf(startNums[1]))*256*256;
    result += (Long.valueOf(endNums[2]) - Long.valueOf(startNums[2]))*256;
    result += (Long.valueOf(endNums[3]) - Long.valueOf(startNums[3]));
    
    return result;
  }
}