c++ - boost regex pattern syntax confusion -

i using boost regex, confused syntax used boost regex. if want use pattern "bb" match string "aabbcc", have make pattern "bb" ".*bb.*" string matched. wired because in perl don't need add ".*" @ front , end of "bb". did miss boost regex or flavor of boost regex? below simple source code question:

#include <boost/regex.hpp> #include <iostream> #include <string> int main() {     boost::regex regex_bb01("bb");     boost::regex regex_bb02(".*bb");     boost::regex regex_bb03("bb.*");     boost::regex regex_bb04(".*bb.*");      if(boost::regex_match("aabbcc", regex_bb01))         std::cout<<"the regex_bb01 matched\n";     else         std::cout<<"the regex_bb01 not matched\n";     if(boost::regex_match("aabbcc", regex_bb02))         std::cout<<"the regex_bb02 matched\n";     else         std::cout<<"the regex_bb02 not matched\n";     if(boost::regex_match("aabbcc", regex_bb03))         std::cout<<"the regex_bb03 matched\n";     else         std::cout<<"the regex_bb03 not matched\n";     if(boost::regex_match("aabbcc", regex_bb04))         std::cout<<"the regex_bb04 matched\n";     else         std::cout<<"the regex_bb04 not matched\n"; } 

the result looks this:

[root@localhost boostcase]# ./regex_test

the regex_bb01 not matched

the regex_bb02 not matched

the regex_bb03 not matched

the regex_bb04 matched

from boost documentation function regex_match

the algorithm regex_match determines whether given regular expression matches all of given character sequence denoted pair of bidirectional-iterators, algorithm defined follows, main use of function data input validation.

in case want use 'bb' match, need use boost::regex_search instead