Repeated Search

It’s quite convenient to iterate with std::regex_iterator and std::regex_token_iterator over the matched texts. std::regex_iterator supports the matches and their capture groups. std::regex_token_iterator supports more. You can address the components of each capture and by using a negative index, your can access the text between the matches.

std::regex_iterator

C++ defines the following four type synonyms for std::regex_iterator.

typedef cregex_iterator     regex_iterator<const char*>
typedef wcregex_iterator    regex_iterator<const wchar_t*>
typedef sregex_iterator     regex_iterator<std::string::const_iterator>
typedef wsregex_iterator    regex_iterator<std::wstring::const_iterator>

You can use std::regex_iterator to count the occurrences of the words in a text:

std::regex_iterator

// regexIterator.cpp 
...
#include <regex>
...

using std::cout;
std::string text{"That's a (to me) amazingly frequent question...