It would probably work better if you used \\s+ consistently for internal spaces.
In Christ, Steven Watanabe
Thank you Steven, the test below works fine now. Best regards, Mau. BOOST_AUTO_TEST_CASE(example_test) { boost::cmatch res; std::string s = " JETIX 2,957,081 643,225.51 0.00"; static const std::string& REGEX1 = "\\s*(\\w+){1}\\s+([\\d,\\.]+){1}\\s+([\\d,\\.]+){1}\\s+([\\d,\\.]+)\\s*$"; static const std::string& REGEX2 = "\\s*(\\w+){1}\\s+(\\w+){1}\\s+(\\w+){1}\\s+([\\d,\\.]+){1}\\s+([\\d,\\.]+){1}\\s+([\\d,\\.]+){1}\\s*$"; boost::regex rx(REGEX1); if (boost::regex_match (s.c_str(), res, rx)) { BOOST_CHECK_EQUAL ("JETIX" , res[1]); BOOST_CHECK_EQUAL ("2,957,081" , res[2]); BOOST_CHECK_EQUAL ("643,225.51", res[3]); BOOST_CHECK_EQUAL ("0.00" , res[4]); } else { BOOST_FAIL ("It was supposed to match."); } boost::cmatch res2; boost::regex rx2(REGEX2); bool match = boost::regex_match (s.c_str(), res2, rx2); for (unsigned i = 0; i < res2.size (); ++i) std::cout << res2[i] << std::endl; if (match) BOOST_FAIL ("It was NOT supposed to match."); }