Is there a standard C++ function object for taking apart a std::pair?

Question

Does anyone know if there\'s a de-facto standard (i.e., TR1 or Boost) C++ function object for accessing the elements of a std::pair? Twice in the past 24 hours I\'ve wished

Answer 1

boost::bind is often used to adapt std::map containers for use with algorithms. Here is an example:

void print_string(const std::string& s) {
  std::cout << s << '\n';
}


std::map my_map;
my_map[0]="Boost";
my_map[1]="Bind";


std::for_each(my_map.begin(), my_map.end(),
              boost::bind(&print_string, boost::bind(
              &std::map::value_type::second,_1)));