c++ - Boost::tokenizer point separated, but also keeping empty fields -

i have seen this question , mine similar it, different, please not mark duplicate.

my question is: how empty fields string?

i have string std::string s = "this.is..a.test"; , want fields <this> <is> <> <a> <test>.

i have tried

typedef boost::char_separator<char> chsep; typedef boost::tokenizer<chsep> tknchsep; chsep sep(".", ".", boost::keep_empty_tokens); tknchsep tok(s, sep); (tknchsep::iterator beg = tok.begin(); beg != tok.end(); ++beg) {   std::cout << "<" << *beg << "> "; } 

but <this> <.> <is> <.> <> <.> <a> <test>.

the second argument boost.tokenizer's char_separator kept_delims parameter. used specify delimiters show tokens. original code specifying "." should kept token. resolve this, change:

chsep sep(".", ".", boost::keep_empty_tokens); 

to:

chsep sep(".", "", boost::keep_empty_tokens);             // ^-- no delimiters show tokens. 

---

here complete example:

#include <iostream> #include <string> #include <boost/foreach.hpp> #include <boost/tokenizer.hpp>  int main() {   std::string str = "this.is..a.test";   typedef boost::tokenizer<boost::char_separator<char> > tokenizer;   boost::char_separator<char> sep(       ".", // dropped delimiters       "",  // kept delimiters       boost::keep_empty_tokens); // empty token policy    boost_foreach(std::string token, tokenizer(str, sep))   {     std::cout << "<" << token << "> ";   }   std::cout << std::endl; } 

which produces desired output:

<this> <is> <> <a> <test>