Convert an IP address to IP number with PHP, ASP, C# and VB.Net
So you've retrieved the visitor's IP address. If you're just logging or tracing it, that's all you need to do. However, if you want to match it to an IP location database, you can't search by the IP in the IPV4 format. It needs to be converted to its IP number equivalent (it is just more efficient to store and search between a range of numbers in database). Here are the functions in PHP, ASP, C# and VB.Net to convert and IP address from dot format to IP number format.
Each function is based on the fact that IP addresses (IPV4) are divided into 4 sub-blocks. Each sub-block has a different weight number, each powered by 256. Here's the math:
IP Number = (16777216*a) + (65536*b) + (256*c) + (d (1))
- where the IP Address = a.b.c.d
And here are the functions that implement that math:
Convert with PHP:
{
if ($IPaddress == "") {
return 0;
} else {
$ips = split ("\.", "$IPaddress");
return ($ips[3] + $ips[2] * 256 + $ips[1] * 256 * 256 + $ips[0] * 256 * 256 * 256);
}
}
Convert IP address to integer with ASP:
Dim i, pos, PrevPos, num
If IPaddress = "" Then
IPAddressToNumber = 0
Else
For i = 1 To 4
pos = InStr(PrevPos + 1, IPaddress, ".", 1)
If i = 4 Then
pos = Len(IPaddress) + 1
End If
num = Int(Mid(IPaddress, PrevPos + 1, pos - PrevPos - 1))
PrevPos = pos
IPAddressToNumber = ((num Mod 256) * (256 ^ (4 - i))) + IPAddressToNumber
Next
End If
End Function
Here's the C# code:
{
int i;
string [] arrDec;
double num = 0;
if (IPaddress == "")
{
return 0;
}
else
{
arrDec = IPaddress.Split('.');
for(i = arrDec.Length - 1; i >= 0 ; i –)
{
num += ((int.Parse(arrDec[i])%256) * Math.Pow(256 ,(3 - i )));
}
return num;
}
}
And here's the VB.NET function to convert an IP address to IP number
Dim arrDec() As String
Dim i As Integer
Dim intResult As Long
If IPaddress = "" then
IPAddressToNumber = 0
Else
arrDec = IPaddress.Split(".")
For i = arrDec.Length - 1 To 0 Step -1
intResult = intResult + ((Int(arrDec(i)) Mod 256) * Math.Pow(256, 3 -i))
Next
IPAddressToNumber = intResult
End If
End Function
Digg this
post to del.icio.us
on January 2nd, 2007 at 5:57 am
Thank you for sharing this.
Here is a small performance improvement to the PHP version:
if ($IPaddress == ") {
return 0;
} else {
$ips = explode('.', $IPaddress);
return ($ips[3] + $ips[2] * 256 + $ips[1] * 65536 + $ips[0] * 16777216);
}
}
on January 5th, 2007 at 5:48 pm
ASP could be improved by doing this
If IPaddress = "" Then
IPAddressToNumber = 0
Else
ips = Split(IPAddress,".")
IPAddressToNumber = ((ips[3])+(ips[2]*256)+(ips[1] * 65536)+(ips[0] * 16777216))
End If
End Function
on January 5th, 2007 at 5:58 pm
Likewise the C# could look a bit more like this
{
string [] arrDec;
int num = 0;
if (IPaddress != "")
{
arrDec = IPaddress.Split('.');
num = (int.Parse(arrDec[3]))+(int.Parse(arrDec[2])*256)+(int.Parse(arrDec[1])*65536)+(int.Parse(arrDec[0])*16777216));
}
return num;
}
on January 5th, 2007 at 6:00 pm
of course the last one won't work
{
string [] arrDec;
int num = 0;
if (IPaddress != "")
{
arrDec = IPaddress.Split('.');
num = (int.Parse(arrDec[3]))+(int.Parse(arrDec[2])*256)
+(int.Parse(arrDec[1])*65536)+(int.Parse(arrDec[0])*16777216));
}
return num;
}
Sorry Bout that
on March 27th, 2007 at 12:51 pm
No need to reinvent the wheel — the .NET Framework already does this:
Shared Function IPAddressToNumber(ByVal IPAddress As String) As Long
Return System.Net.IPAddress.Parse(IPAddress).Address
End Function
Note also, an Integer is signed, trying to convert, say "128.0.0.1" will cause an arithmetic overflow exception unless you use a Long.
&H80000001 is a negative number
on April 11th, 2007 at 7:49 pm
WOW cool thanks! I was looking how to do this in PHP for ages.
on May 15th, 2007 at 4:59 am
http://www.php.net/ip2long
on July 17th, 2007 at 6:54 am
PHP is the easiest way!
on October 27th, 2007 at 2:58 am
Your code is redundant for PHP - what Metin said, this function is built in to PHP - see http://www.php.net/ip2long
on April 21st, 2008 at 4:45 am
Apart from the fact that the PHP method being redundant, your code gives differing values from the actual ones which should occur. For example, the IP address 212.58.240.0 equates to 3560632320 with your method, but i actually -734334976 everywhere else. In fact, your code will never produce a negative number, which an actual IP Number can be.