Richard Hadsell wrote:

I am having a problem with a regex_match in Boost 1.33.0. Perhaps I am missing something; perhaps it is a bug that has been fixed.

The pattern "[+-]?(\\d+(\\.\\d*)?|\\.\\d+)([Ee][+-]?\\d+)?" should match only floating-point numbers that can be read by sscanf. (Extra escape characters are for C++, of course.) Yet regex_match returns true for "3.6.5".

I guessed that the problem might be in the '(...)?' expression just before the alternative operator '|', so I tried this: "[+-]?(\\d+|\\d+\\.\\d*|\\.\\d+)([Ee][+-]?\\d+)?". With this pattern regex_match returns false for "3.6.5". I am using it, but I consider it a workaround.

Can someone explain what I have missed or whether this is a bug?

I can't reproduce this with 1.33.1 (there were some regex bugs fixed in the .1 release), my test case is: int main(int argc, char* argv[]) { try { boost::regex e("[+-]?(\\d+(\\.\\d*)?|\\.\\d+)([Ee][+-]?\\d+)?"); std::string text = "3.6.5"; if(boost::regex_match(text, e)) { std::cout << "Matched!!!" << std::endl; } } catch (const std::exception& e) { std::cout << e.what() << std::endl; } return 0; } Can you please try again with 1.33.1? Thanks, John.