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 what you look for.

boost::bind(&std::pair::second, _1); // returns the value of a pair

Example:

typedef std::map map_type;

std::vector values; // will contain all values
map_type map;
std::transform(map.begin(), 
               map.end(), 
               std::back_inserter(values), 
               boost::bind(&map_type::value_type::second, _1));