#include <string>
#include <iostream>
#include <boost/algorithm/string.hpp>
int main()
{
        std::string str = "This is a      test string";

        for( boost::algorithm::split_iterator<std::string::iterator> i
//    = make_split_iterator(str, token_finder(is_space()));
            = make_split_iterator(str, token_finder(
                                        boost::algorithm::is_space(),
                                        boost::algorithm::token_compress_on));
             i != boost::algorithm::split_iterator<std::string::iterator>();
             ++i)
        {
                std::cout << *i << '\n';
        }
}