Dr John Maddock, Here is a test case. int main(int argc, char* argv[]) { boost::regex expression; std::string asFind[5]; expression.assign("(?!foo)bar", boost::regbase::perl); asFind[0] = "foobar"; asFind[1] = "??bar"; asFind[2] = "barfoo"; asFind[3] = "bar??"; asFind[4] = "bar"; for( int i = 0; i < 5; i++ ){ std::string s = asFind[i]; std::string::const_iterator start = s.begin(); std::string::const_iterator end = s.end(); boost::match_resultsstd::string::const_iterator subexp; if (boost::regex_search( start, end, subexp, expression, boost::match_default)) { printf( "%s - Found.\n", s.c_str() ); } else { printf( "%s - Not Found.\n", s.c_str() ); } } return 0; } The output is: foobar - Not Found. ??bar - Not Found. barfoo - Found. bar?? - Found. bar - Found. However, all the words should be "Found". Thank you for your time in advance. Yutaka Emura -----Original Message-----
"(?!foo)bar" matches "bar" in the last three lines of the following:
foobar ??bar barfoo bar?? bar
Why doesn't it match "bar" in all the lines?
Provided you are calling regex_search it should find a match in all the cases, if it doesn't then please submit a test case.