Re: [Boost-users] Simple regex question

From: John Maddock (john_at_[hidden])
Date: 2007-07-04 08:40:43

david v wrote:
> Ok i understand david and divad is the same so it's normal to find it
> twice, however why it always return as match "David" and not both
> matches "david" and "divad" in the order they appear in the searched
> string??? does not make sense to me ?? How can i get the matches in
> the same order they appear in the string ??

You missed my point: according to your own program output they are *not* 
both present in the string being searched.

John.

> david v wrote:
>>> Hello,
>>> I'm trying to use regex_search to look for regular expressions.
>>>
>>> regex = (david|divad)
>>> stringtosearch = "david"
>>>
>>>
>>> So I'm looking for regex above in the string "david". As you see a
>>> very basic example. I'm expecting to find two hits, but I thought I
>>> should recover "david" and "david" and not twice the same match
>>> "david" ???
>>>
>>> Here is a snippet of the code:
>>>
>>> ....
>>> boost::smatch match;
>>> start = stringtosearch.begin(); //that would be the start of "david"
>>> end = stringtosearch.end(); // that would be the end of "david"
>>> old_pos = 0;
>>> cout << "Looking for regex:" << regex << " in string " <<
>>> stringtosearch << endl;
>>> while (boost::regex_search(start,end,match,regex))
>>>      {
>>>
>>>
>>> old_pos += match.position()+1;
>>> std::string t = match[0];
>>>
>>> std::cout << "\tFound:" << match[0] << endl;
>>>
>>> old_pos += match.length();
>>> start = match[0].second;
>>>
>>>
>>>  }
>>>  catch(const std::exception &regex)
>>>    {
>>>      std::cerr << "Exception:" << regex.what() << std::endl;
>>>      exit(-1);
>>>    }
>>>
>>>
>>> Here is the output:
>>> Looking for regex:(david|divad) in string david
>>> Found david
>>> Looking for regex:(david|divad) in string david
>>> Found david
>>>
>>> As you can see, pattern "david" is found twice ??? I was expecting
>>> two different patterns to be found "david" and "divad".
>
> Um, because the stringtosearch contains "divad" both times the code is
> called?
>
>>> cout << "Looking for regex:" << regex << " in string " <<
>>> stringtosearch << endl;
>
> Outputs
>
>>> Looking for regex:(david|divad) in string david
>
> Both times.
>
>>> By the way how can I recover the total number of matches found ??
>
> By keeping count?
>
> John.
>
> _________________________________________________________________
> Testez Windows Live Mail Beta ! http://www.ideas.live.com/
>
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/boost-users