RegEx for an IP Address

Solution 1:

The [ shouldn't be at the start of your pattern. Also, you probably want to use Matches(...).

Try:

String input = @"var product_pic_fn=;var firmware_ver='20.02.024';var wan_ip='92.75.120.206';if (parent.location.href != window.location.href)";
Regex ip = new Regex(@"\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b");
MatchCollection result = ip.Matches(input);
Console.WriteLine(result[0]);

Solution 2:

Very old post, you should use the accepted solution, but consider using the right RegEx for an IPV4 adress :

((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)

If you want to avoid special caracters after or before you can use :

^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$

Solution 3:

Try this:

 Match match = Regex.Match(input, @"\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}");
 if (match.Success)
 {
     Console.WriteLine(match.Value);
 }

Solution 4:

If you just want check correct IP use IPAddress.TryParse

using System.Net;

bool isIP(string host)
{
    IPAddress ip;
    return IPAddress.TryParse(host, out ip);
}

Solution 5:

I know this post isn't new, but, I've tried several of the proposed solutions and none of them work quite as well as one I found thanks to a link provided by Justin Jones. They have quite a few for IP Address but this is the top of the list and using LinqPad (I LOVE LinqPad) most tests I've thrown at it work extremely well. I recommend utilizing this one rather than any of the previous provided expressions:

^(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])$

Give that a shot in LinqPad with the following:

// \b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b  355.168.0.1 = 355.168.0.1 (Not Correct)
// ((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?) 355.168.0.1 = 55.168.0.1 (Not correct)
// \d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}  355.168.0.1 = 355.168.0.1 (Not Correct)
// ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$  355.168.0.1 = 355.168.0.1 (Not Correct)
// ^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$  355.168.0.1 = 355.168.0.1 (Not Correct)
// ^(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])$  355.168.0.1 = No Match (Correct)

Match match = Regex.Match("355.168.0.1", @"^(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])$");
if (match.Success) {
    Console.WriteLine(match.Value);
}
else {
    Console.WriteLine("No match.");
}

With the new RegEx this is not valid which is correct: 355.168.0.1 = No Match which is correct as noted in the comments.

I welcome any tweaks to this as I'm working on a tool that is making use of the expression and am always looking for better ways of doing this.

UPDATE: I've created a .NET Fiddle project to provide a working example of this expression along with a list of IP Addresses that test various values. Feel free to tinker with it and try various values to exercise this expression and provide any input if you find a case where the expression fails. https://dotnetfiddle.net/JoBXdI

UPDATE 2: Better yet refer to this post: Another related question.

Thanks and I hope this helps!