Re: [Boost-users] Regex Submatch Position Question

From: Lynn Allan (l_d_allan_at_[hidden])
Date: 2006-04-10 16:24:17

Michael Coles, MCDBA wrote:
> I'm taking a look at
> http://www.boost.org/libs/regex/doc/captures.html but I'm not seeing
> how to access the capture start location with match_extra? I'll keep
> digging but if anyone out there knows of a shortcut to the answer,
> it'd be appreciated.

<alert comment="boost newbie">

Here's some code adapted from the regex chapter in:
"Beyond the C++ Standard Library ... an Introduction to Boost:

#include <iostream>
#include <boost/regex.hpp>
class regex_callback {
private:
  int sum_;
public:
  regex_callback() : sum_(0) {}

  template <typename T> void operator() (const T& what) {
    sum_ += atoi(what[1].str().c_str());
    std::cout << "Position: " << what.position(1)
            << " Length: " << what.length(1)
           << std::endl;
  }

   int sum() const
  {
      return sum_;
  }
};

int main(int argc, char** argv)
{
   boost::regex reg("(\\d+),?");
   std::string s="1,1,2,3,5,8,13,21";
   boost::sregex_iterator it(s.begin(), s.end(), reg);
   boost::sregex_iterator end;
   regex_callback c;
   int sum = for_each(it, end, c).sum();
   std::cout << "Sum: " << sum << std::endl;
   return 0;
}

</alert>

>
> -----Original Message-----
> From: boost-users-bounces_at_[hidden]
> [mailto:boost-users-bounces_at_[hidden]] On Behalf Of Lynn Allan
> Sent: Friday, April 07, 2006 6:04 PM
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] Regex Submatch Position Question
>
> If I understand your question, the snippet sample code related to
> "Captures"
>
> can be adapted:
> http://www.boost.org/libs/regex/doc/captures.html
>
> HTH
>
> ----- Original Message -----
> From: <admin_at_[hidden]>
> Newsgroups: gmane.comp.lib.boost.user
> Sent: Friday, April 07, 2006 12:19 PM
> Subject: Regex Submatch Position Question
>
>
>> Hi all,
>>
>> Quick question about the Boost::Regex library.  Is there a way to
>> identify, with sub-matches, where a match in the search string is
>> made and the length of the match?  For instance, with the following
>> regular expression and search string:
>>
>> Regex ==> "(\d+)"
>> Search String ==> "Give me 100 dollars or give me 2001 dollars."
>>
>> Is there a way to determine that the subexpression matched at
>> positions 8 and 31 in the search string, and that the lengths of 
>> the
>> matches were three and four characters?
>>
>> Thanks
>
>
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