How do you parse an IP address string to a uint value in C#?

Question

I'm writing C# code that uses the windows IP Helper API. One of the functions I'm trying to call is "GetBestInterface" that takes a 'uint' representation of an IP. What I need is to parse a textual representation of the IP to create the 'uint' representation.

I've found some examples via Google, like this one or this one, but I'm pretty sure there should be a standard way to achieve this with .NET. Only problem is, I can't find this standard way. IPAddress.Parse seems to be in the right direction, but it doesn't supply any way of getting a 'uint' representation...

There is also a way of doing this using IP Helper, using the ParseNetworkString, but again, I'd rather use .NET - I believe the less I rely on pInvoke the better.

So, anyone knows of a standard way to do this in .NET?

Answer 1

MSDN says that IPAddress.Address property (which returns numeric representation of IP address) is obsolete and you should use GetAddressBytes method.

You can convert IP address to numeric value using following code:

var ipAddress = IPAddress.Parse("some.ip.address");
var ipBytes = ipAddress.GetAddressBytes();
var ip = (uint)ipBytes [3] << 24;
ip += (uint)ipBytes [2] << 16;
ip += (uint)ipBytes [1] <<8;
ip += (uint)ipBytes [0];

EDIT:
As other commenters noticed above-mentioned code is for IPv4 addresses only. IPv6 address is 128 bits long so it's impossible to convert it to 'uint' as question's author wanted.

Answer 2

Shouldn't it be:

var ipAddress = IPAddress.Parse("some.ip.address");
var ipBytes = ipAddress.GetAddressBytes();
var ip = (uint)ipBytes [0] << 24;
ip += (uint)ipBytes [1] << 16;
ip += (uint)ipBytes [2] <<8;
ip += (uint)ipBytes [3];

?

Answer 3

var ipuint32 = BitConverter.ToUInt32(IPAddress.Parse("some.ip.address.ipv4").GetAddressBytes(), 0);`

This solution is easier to read than manual bit shifting.

See How to convert an IPv4 address into a integer in C#?

Answer 4

Also you should remember that IPv4 and IPv6 are different lengths.

Answer 5

Byte arithmetic is discouraged, as it relies on all IPs being 4-octet ones.

Answer 6

System.Net.IPAddress ipAddress = System.Net.IPAddress.Parse("192.168.1.1");

byte[] bytes = ipAddress.GetAddressBytes();
for (int i = 0; i < bytes.Length ; i++)
       Console.WriteLine(bytes[i]);

Output will be 192 168 1 1

Answer 7

I have never found a clean solution (i.e.: a class / method in the .NET Framework) for this problem. I guess it just isn't available except the solutions / examples you provided or Aku's example. :(

Answer 8

Complete solution:

public static uint IpStringToUint(string ipString)
{
    var ipAddress = IPAddress.Parse(ipString);
    var ipBytes = ipAddress.GetAddressBytes();
    var ip = (uint)ipBytes [0] << 24;
    ip += (uint)ipBytes [1] << 16;
    ip += (uint)ipBytes [2] <<8;
    ip += (uint)ipBytes [3];
    return ip;
}

public static string IpUintToString(uint ipUint)
{
    var ipBytes = BitConverter.GetBytes(ipUint);
    var ipBytesRevert = new byte[4];
    ipBytesRevert[0] = ipBytes[3];
    ipBytesRevert[1] = ipBytes[2];
    ipBytesRevert[2] = ipBytes[1];
    ipBytesRevert[3] = ipBytes[0];
    return new IPAddress(ipBytesRevert).ToString();
}

Reverse order of bytes:

public static uint IpStringToUint(string ipString)
{
    return BitConverter.ToUInt32(IPAddress.Parse(ipString).GetAddressBytes(), 0);
}

public static string IpUintToString(uint ipUint)
{
    return new IPAddress(BitConverter.GetBytes(ipUint)).ToString();
}

You can test here:

https://www.browserling.com/tools/dec-to-ip

http://www.smartconversion.com/unit_conversion/IP_Address_Converter.aspx

http://www.silisoftware.com/tools/ipconverter.php