I have having a problem determining if the regex library is working properly. I have run the regex regression tests, and all tests in the test.txt file pass. My problem however began with the following match: string: "orange and ba.ana and kiwi" expression: "\\.([a-z]+).*[ \t\n].*\\.([a-z]+)" expected result: match, captures 'range' and 'ana' real result: no match The code in question is this: bool result = false; std::string str = "orange and ba.ana and kiwi"; std::string exp(".([a-z]+).*[ \t\n].*\\.([a-z]+)"); try { boost::smatch what; boost::regex e(exp.c_str()); // use default format flags result = regex_match(str, what, e); if (result) { ... } } catch (std::runtime_error &e) { ... } ... It seems to consistently fail. This same example works in both Java and Perl, and with the PCRE C++ regex library. No exception is being caught either. I posted the actual code to show that i don't think i'm doing anything particularly unique - i call regex_match (though even regex_search fails to match). I even tried formatting a file for the regression test harness with this example, and it confirmed that this particular example does not succeed. Can someone please provide suggestions regarding: a) what is going wrong b) how to fix it It should be noted that i'm running linux, boost version 1.31.0, with the regex patch installed. Thanks.