Comments on: Convert an IP address to IP number with PHP, ASP, C# and VB.Net http://www.justin-cook.com/wp/2006/11/28/convert-an-ip-address-to-ip-number-with-php-asp-c-and-vbnet/ A web, technology, programming and SEO blog by Justin Cook Sun, 12 Oct 2008 00:41:05 +0000 http://wordpress.org/?v=2.6 By: Nick Critten http://www.justin-cook.com/wp/2006/11/28/convert-an-ip-address-to-ip-number-with-php-asp-c-and-vbnet/#comment-148727 Nick Critten Thu, 25 Sep 2008 12:19:58 +0000 http://www.justin-cook.com/wp/2006/11/28/convert-an-ip-address-to-ip-number-with-php-asp-c-and-vbnet/#comment-148727 @Ashley Sheridan This is incorrect, a negative numbered IP number is simply an indication that the wrong datatype is being used to store it. IP Addresses are actually a 32bit binary number, in decimal these are values between 0 (0.0.0.0) and 4294967295 (255.255.255.255) On 32Bit Computer Systems (i.e. most PCs & servers out there today), an UNSIGNED integer value has the range 0-4294967295. A SIGNED Interger will have the range −2147483648 to +2147483647. This is because 1 bit is "Wasted" as the sign. However PHP (for reasons that are completely beyond me) doesn't support unsigned integers. For this reason, IP numbers in PHP *should* be stored as FLOATs AKA DOUBLEs However, PHPs ip2long function returns a signed integer value, rather that the long value implied. This means that any IP address higher than 127.255.255.255 gets a negative value, which is incorrect. The following function returns a properly formatted float. function myip2long($ip){ return floatval(sprintf("%u",ip2long('$ip'))); } @Ben Faust Your function returns the number as a string value, instead of a number, (not a big problem in PHP I know) but why do you pad the result out to 10 digits with 0's ? @Ashley Sheridan

This is incorrect, a negative numbered IP number is simply an indication that the wrong datatype is being used to store it.
IP Addresses are actually a 32bit binary number, in decimal these are values between 0 (0.0.0.0) and 4294967295 (255.255.255.255)

On 32Bit Computer Systems (i.e. most PCs & servers out there today), an UNSIGNED integer value has the range 0-4294967295. A SIGNED Interger will have the range −2147483648 to +2147483647. This is because 1 bit is "Wasted" as the sign.

However PHP (for reasons that are completely beyond me) doesn't support unsigned integers. For this reason, IP numbers in PHP *should* be stored as FLOATs AKA DOUBLEs

However, PHPs ip2long function returns a signed integer value, rather that the long value implied. This means that any IP address higher than 127.255.255.255 gets a negative value, which is incorrect.

The following function returns a properly formatted float.

function myip2long($ip){
return floatval(sprintf("%u",ip2long('$ip')));
}

@Ben Faust

Your function returns the number as a string value, instead of a number, (not a big problem in PHP I know) but why do you pad the result out to 10 digits with 0's ?

]]> By: Randall Spychalla http://www.justin-cook.com/wp/2006/11/28/convert-an-ip-address-to-ip-number-with-php-asp-c-and-vbnet/#comment-146801 Randall Spychalla Tue, 16 Sep 2008 15:44:34 +0000 http://www.justin-cook.com/wp/2006/11/28/convert-an-ip-address-to-ip-number-with-php-asp-c-and-vbnet/#comment-146801 The Net call: System.Net.IPAddress.Parse(IPAddress).Address has been deprecated by Microsoft in VS 2008 due to being extremely buggy. It won't correctly handle quite a few addresses. The Net call: System.Net.IPAddress.Parse(IPAddress).Address has been deprecated by Microsoft in VS 2008 due to being extremely buggy. It won't correctly handle quite a few addresses.

]]> By: Ben Faust http://www.justin-cook.com/wp/2006/11/28/convert-an-ip-address-to-ip-number-with-php-asp-c-and-vbnet/#comment-137106 Ben Faust Tue, 29 Jul 2008 21:40:54 +0000 http://www.justin-cook.com/wp/2006/11/28/convert-an-ip-address-to-ip-number-with-php-asp-c-and-vbnet/#comment-137106 In PHP, this can be done more simply, like this: function ip_address_to_number( $IPAddress ) { return sprintf("%010u", ip2long( $IPAddress ) ); } In PHP, this can be done more simply, like this:

function ip_address_to_number( $IPAddress )
{
return sprintf("%010u", ip2long( $IPAddress ) );
}

]]>