It would be nice if tokenizer documentation clearly explains that tokenizer constructor is not making a copy of its input data, thus passing temporary value as first argument to its constructor invites undefined behaviour. Following code can be given as an example of such undefined behaviour: #include <string> #include <iostream> #include <boost/tokenizer.hpp> using namespace std; using namespace boost; int main() { typedef tokenizer<char_separator<char>, string::const_iterator, string> Tokenizer; const char_separator<char> semicolon(";"); Tokenizer tokens(std::string("a;b;c"), semicolon); string t("x;y;z"); for (Tokenizer::const_iterator i = tokens.begin(); i != tokens.end(); ++i) std::cout << *i << std::endl; } (program may produce different output depending on compiler and its options, or simply crash) B.