Access elements of boost tokenizer - c++

Question

I'm trying to assign columns of a file using boost to a std::map. I would like to assign element 0 from each line to the index and element 2 to the value. Is there a way to do this without an iterator? The addr_lookup line does not work.
#include <iostream>
#include <fstream>
#include <string>
#include <map>
#include <boost/tokenizer.hpp>
#include <boost/lexical_cast.hpp>
int main()
{
std::ifstream myfile("core_info_lowbits.tab", std::ios_base::in);
std::string line;
typedef boost::tokenizer<boost::char_separator<char> > tokenizer;
boost::char_separator<char> sep(" ");
std::map<std::string, unsigned int> addr_lookup;
while ( std::getline (myfile,line) )
{
tokenizer tokens(line, sep);
//Line below does not work
addr_lookup[*tokens.begin()] = boost::lexical_cast<unsigned int> (*(tokens.begin()+2));
for (tokenizer::iterator tok_iter=tokens.begin();
tok_iter != tokens.end(); ++tok_iter)
std::cout << *tok_iter << std::endl;
}
}

Answer 1

You are trying to advance the iterator using +, which is not possible
Use:
tokenizer::iterator it1,it2= tokens.begin();
it1=it2;
++it2; ++it2;
addr_lookup[*it1] = boost::lexical_cast<unsigned int> (*it2);
Or simply,
tokenizer::iterator it1,it2= tokens.begin();
it1=it2;
std::advance(it2,2);
addr_lookup[*it1] = boost::lexical_cast<unsigned int> (*it2);