Hi All I am trying to use boost lambda for looping over a std::map to get each element and pass those to a class function using lambda functions. I don't know why but the binding inside my std::for_each is not compiling and I have 2 errors pointing to the line where boost::assign is used. 'invalid initialization of reference of type int&' 'invalid initialization of reference of type std::basic_string<>&' Do you know how to fix this and why it is happening Thank you very much Regards CS //Boost //#include<boost/assign/std/map.hpp> #include<boost/assign/list_of.hpp> #include<boost/lambda/lambda.hpp> #include<boost/lambda/core.hpp> #include<boost/lambda/bind.hpp> #include<boost/lambda/construct.hpp> class CInnerClassHandler{ public: void DoSomething( int aIntValue, const std::string& aStringValue ){ std::cout << "INT:" << aIntValue << "STRING:" << aStringValue << std::endl; // here we just trace } }; void map_lambda_test(){ typedef std::pair< int, std::string > this_pair; std::map< int, std::string > dictionary = boost::assign::map_list_of(3,"A")(4,"B")(5,"C"); // Errors points to // this line of code CInnerClassHandler obj; std::for_each( dictionary.begin(), dictionary.end(), boost::lambda::bind( &CInnerClassHandler::DoSomething, &obj, boost::lambda::bind(&this_pair::first, boost::lambda::_1), boost::lambda::bind(&this_pair::second,boost::lambda::_1)) ); }