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

How about this?

items.reserve(pairs.size());
for (size_t it = 0; it < pairs.size(); ++it) {
    items.push_back(pairs[it].first);
}

Simple to understand and debug.