boost regex sub-string match

Question

I want to return output "match" if the pattern "regular" is a sub-string of variable st. Is this possible?

int main()
{
  string st = "some regular expressions are Regxyzr";

  boost::regex ex("[Rr]egular");
  if (boost::regex_match(st, ex)) 
  {
    cout << "match" << endl;
  }
  else 
  {
    cout << "not match" << endl;
  }
}

Answer 1

The boost::regex_match only matches the whole string, you probably want boost::regex_search instead.

Answer 2

regex_search does what you want; regex_match is documented as

determines whether a given regular expression matches all of a given character sequence

(the emphasis is in the original URL I'm quoting from).