how to find whether a string contains HOST NAME or IP ADDRESS

Question

_{Thursday, August 9, 2007 2:25 PM | 1 vote}

hello all,
i have one input variable as a String.
if it is IP Address then i have to find HOSTNAME.
if it is HOSTNAME then i have to find IP Address.
i can use any API for getting IP or HOST only after knowing whether the input is HOST or IP.
any body please help in finding the input is IP or HOST
Regards
R

All replies (6)

_{Thursday, August 9, 2007 3:30 PM ✅Answered}

You could try Dns.GetHostEntry.  It returns an IPHostEntry which you can use the AddressList property and the IPAddress.ToString to compare the IP address to your original string to see if it was an IP Address.  Example:

Code Snippet

  String nameOrAddress = "127.0.0.1";
  IPHostEntry hostEntry = Dns.GetHostEntry(nameOrAddress);
  if(hostEntry.AddressList[0].ToString() == nameOrAddress)
   Console.WriteLine("{0} is IP", nameOrAddress);
  else
   Console.WriteLine("{0} is hostname", nameOrAddress);
  nameOrAddress = "localhost";
  hostEntry = Dns.GetHostEntry(nameOrAddress);
  if(hostEntry.AddressList[0].ToString() == nameOrAddress)
   Console.WriteLine("{0} is IP", nameOrAddress);
  else
   Console.WriteLine("{0} is hostname", nameOrAddress);

_{Thursday, August 9, 2007 6:16 PM ✅Answered}

You sure can use a regular expression

http://www.codeproject.com/dotnet/RegexTutorial.asp has an example of finding an IP address, and should be read if you're starting out with regular expressions

Here it is if you're lazy

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

Of course, that will only prove if it is an IP address or not, it doesn't prove that it's a proper host

Anyway, have fun,

-mwalts

_{Thursday, August 9, 2007 2:44 PM}

Check this IPAddress Class. The example in that might help you

_{Thursday, August 9, 2007 3:48 PM}

You can also use a regular expression to check if it's a ip-address.

_{Friday, August 10, 2007 4:07 AM}

thank you  very much all of u guys

_{Saturday, August 11, 2007 9:48 AM | 1 vote}

Yesterday I read that the IPAddress class has a static TryParse method. This would probably be the best solution for your intention.