Copy vector of object to vector of shared_ptrs

Question

I have a simple struct and vector of its objects. And I want to move all objects to the vector of shared_ptrs. I don't need the initial vector anymore. I presented you with my situation.

Is my approach correct? I want to do this the most effective way:

struct MyStruct
{
    int i_;
    std::string s_;
};

void copyVector(std::vector< MyStruct>&& vt)
{
    std::vector<std::shared_ptr<MyStruct>> ptrsVt;


    for (auto& v : vt)
        ptrsVt.push_back(std::make_shared<MyStruct>(std::move(v)));

    // ...
}

void processing()
{
    std::vector<MyStruct> vt = getVectorFromSomewhere();

    copyVector(std::move(vt));
}

Answer 1

Yes, that's correct. You might want to reserve the size of the destination beforehand though:

#include <algorithm>
#include <cstdio>
#include <iterator>
#include <memory>
#include <string>
#include <utility>
#include <vector>

template <class T>
auto transform_vector(std::vector<T>&& src) -> std::vector<std::shared_ptr<T>> {
  std::vector<std::shared_ptr<T>> dst;
  dst.reserve(src.size());

  transform(begin(src), end(src), back_inserter(dst),
            [](T& elm) { return std::make_shared<T>(std::move(elm)); });

  return dst;
}

int main() {
  std::vector<std::string> elms{"a", "b", "c"};
  auto ptrs = transform_vector(std::move(elms));

  for (auto const& elm : elms) {
    std::printf("\"%s\", ", elm.c_str());  // moved strings, possibly empty
  }

  std::putchar('\n');

  for (auto const& ptr : ptrs) {
    std::printf("\"%s\", ", ptr->c_str());  // "a", "b", "c"
  }

  std::putchar('\n');
}