c++ - Count number of matches

Question

How do I count the number of matches using C++11's std::regex?

std::regex re("[^\s]+");
std::cout << re.matches("Harry Botter - The robot who lived.").count() << std::endl;

Expected output:

7

Answer 1

You can use regex_iterator to generate all of the matches, then use distance to count them:

std::regex  const expression("[^\s]+");
std::string const text("Harry Botter - The robot who lived.");

std::ptrdiff_t const match_count(std::distance(
    std::sregex_iterator(text.begin(), text.end(), expression),
    std::sregex_iterator()));

std::cout << match_count << std::endl;