Get the index of all matches using regex_search?

Question

I just start to learn how to use regex for string handling (C++11 new feature). Please pardon me if the following question is too silly.

Cu

Answer 1

A single execution of regex_search gives you only one match (whose size and position you queried).

You could: change your regex to match the substring more than once (and then loop over the capture groups), or just use regex_iterator

string str = "aaabxxxaab";
regex rx("ab");

vector<int> index_matches; // results saved here 
                           // (should be {2, 8}, but always get only {2})

for(auto it = std::sregex_iterator(str.begin(), str.end(), rx);
    it != std::sregex_iterator();
     ++it)
{
    index_matches.push_back(it->position());
}

online demo: http://coliru.stacked-crooked.com/a/4d6e1a44b60b7da5