CODEWITHSUNDEEP
c++regex
Ning
Ning

Reputation: 199

How to use regex_token_iterator<std::string::iterator> get submatch's position of original string by the iterator itself?

Below is the code to find the match of "\b(sub)([^ ]*)" in "this subject has a submarine as a subsequence". But I also want to know the position of those sub matches in original string by regex_token_iterator itself. The result should be 5, 19, 34. 

// regex_token_iterator example
#include <iostream>
#include <string>
#include <regex>

int main ()
{
  std::string s ("this subject has a submarine as a subsequence");
  std::regex e ("\\b(sub)([^ ]*)");   // matches words beginning by "sub"

  // default constructor = end-of-sequence:
  std::regex_token_iterator<std::string::iterator> rend;

  std::cout << "entire matches:"; 
  std::regex_token_iterator<std::string::iterator> a ( s.begin(), s.end(), e );
  while (a!=rend) std::cout << " [" << *a++ << "]";
  std::cout << std::endl;

  return 0;
}

Output:
entire amtches: [subject] [submarine] [subsequence]

Upvotes: 3

Views: 2433

Answers (1)

Hugal31
Hugal31

Reputation: 1768

*a return a pair of two iterators over the string s. You could try this:

std::cout << " [" << *a++ << ' ' << a->first - s.begin() << "]";

or this

std::cout << " [" << *a++ << ' ' <<  std::distance(s.begin(), a->first) << "]";

Upvotes: 6

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