This is my code:

#include <string>
#include <boost/algorithm/string/regex.hpp>
string f(const string& s) {
      using namespace boost::algorithm;
      return replace_regex_copy(s, "\\w", "?");
}

This is what compiler says:

no matching function for call to ‘replace_regex_copy(const
std::basic_string<char, std::char_traits<char>,
std::allocator<char> >&, std::string, std::string)

The link to the library: http://www.boost.org/doc/libs/1_43_0/doc/html/boost/algorithm/replace_regex_copy.html

Could anyone please help? Thanks!

ps. Boost library is in place, since other functions from it work fine.