Thread: strings

...and now it has been done. I wrote a program of about 60 lines, and it adds a dot before extensions of any length. Works like a charm.

surely,one can find the '.' but inserting '.' is not that easy.one should then know all
.com,.tk,.info etc sites .

Well, if you don't know what you are checking for, then I guess that would be a problem.

Finding the '.' is easy - can be done with one for loop.

Why would you ever need to find a dot? It seems to me, the poster wants to correct faulty email addresses that don't have dots separating the extension from the rest of the email address.

But finding where one should be is far harder

That is what the question is.

however if they have something like "myinfo.com", you'd end up with "my.info.com".

With the program I wrote, if you start with "myinfocom", you end up with "myinfo.com", and if you start with "myinfo.com" you end up with no change.

Read the original question. There were two parts to it.

Possibly. The poster would have to clarify what he wants the program to produce for each of the two strings:

yahoo.com
yahoocom

In the first case, I assumed he wanted there to be no change.

Post your code.

I think Bob Vila is still working on the problem. Here is an example of my output, though:

Code:

myinfo.com
myinfocom---->myinfo.com
yahoocom---->yahoo.com
excite.com
partypokernet---->partypoker.net
govnl---->gov.nl
editplus.info
cplusplusinfo---->cplusplus.info
Press any key to continue

You could cheat by getting one TLD (ie ".au"), querying the site to see if it returns a match, and if not cycle through again for another extension ".com.au"

If your scepticism is based on email addresses with a double extension like .com.au, then you are right my program doesn't address those. I used the poster's example of "yahoocom" as my model.

>>Sure it can.
If domains (I'm assuming that's what '.com' etc. are called) are exclusive from right to left, then it can. If this is not the case, however, then:

www.abcdefg.hij
www.abcdefgh.ij

If you are given www.abcdefghij, then you will find two different possible domains. On the other hand, if it is guaranteed that domains will not overlap from right to left (i.e. [.com and .comp] are allowed but [.com and .acom] are not), then you can iterate the string backwards eliminating all domains that do not match until you have one string remaining. The same cannot be said if domains are only guaranteed not to overlap from left to right.

Code:

list<string> domainList;

//dottify() returns true if a unique match was found and the URL has been dotted.
bool dottify(string& s)
{
   list<string> potentialDomains = domainList;

   //Iterate backwards, checking each character with the domains.
   for(string::size_type i = 1; i <= s.size(); ++i)
   {
      list<string>::iterator it = potentialDomains.begin();

      //Check the corresponding character in each domain
      while(it != potentialDomains.end())
      {
         if(it->size() < i)  //Domain is too short
         {
            it = potentialDomains.erase(it);
            continue;
         }

         if((*it)[it->size() - i] != s[s.size() - i])  //Character doesn't match
         {
            it = potentialDomains.erase(it);
            continue;
         }

         ++it;
      }

      if(potentialDomains.size() == 1)   //If only 1 domain matches, see if it works.
      {
         if(potentialDomains.front().size() > s.size())  //Domain is too long
            return false;

         s.insert(s.size() - potentialDomains.front().size(), 1, '.');
         return true;
      }
      else if(potentialDomains.size() == 0)
         return false;
   }

   return false;
}

Note that this is untested, and also that I'm working off the assumption that domains are right-to-left exclusive (gee, I'm making up a lot of words lately..).