RegEx for an IP Address

Question

I try to extract the value (IP Address) of the wan_ip with this sourcecode: Whats wrong?! I´m sure that the RegEx pattern is correct.

String input = @\"var p         


        

Answer 1

Avoid using /b - it allows characters before or after the IP
For example ...198.192.168.12... was valid.

Use ^ and $ instead if you can split the input into chunks that would isolate the IP address.

     Regex regexIP = new Regex(@"^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$");

     if (regexIP.Match(textBoxIP.Text).Success){
         String myIP = textBoxIP.Text;
     }

Note above will not validate the digits, as pointed out 172.316.254.1 was true. This only checks correct formatting.

---

UPDATE: To validate FORMATTING and VALUES you could use

     Regex regexIP = new Regex(@"^([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])$");

     if (regexIP.Match(textBoxIP.Text).Success){
         String myIP = textBoxIP.Text;
     }

(note using ([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5]) for each numeric value)
Credit: https://stackoverflow.com/a/10682785/4480932