C++ std::transform vector of pairs->first to new vector

Question

Sorry for a little bit beginner question. There are vector and vector of pairs

typedef std::vector  TItems;
typedef std::vector < std::pair <         


        

Answer 1

another possibility from C++11 would be std::mem_fn, which is similar to solution with std::bind:

std::transform(pairs.begin(), 
               pairs.end(), 
               std::back_inserter(items), 
               std::mem_fn(&std::pair::first)               
);