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

see frerich's or kotlinski's answer for C++03.

C++11 solution with lambda:

std::transform(pairs.begin(), 
               pairs.end(), 
               std::back_inserter(items), 
               [](const std::pair& p) { return p.first; });