Question

I’m just trying to get more into stl semantics, and converting old loops over to algorithms where appropriate. I’m having trouble figuring out the best way to transform this loop into a call to copy. Any ideas?

    vector< vector<float> > rvec;
    const float * r[Max] = ...;

    // ...

    for (int ri=0; ri<N; ri++)
      for (int rj=0; rj<M; rj++)
        rvec[ri][rj] = r[ri][rj];

Answer 1

rvec.resize(Max);
for (int i = 0; i < Max; ++i) {
  rvec[i].resize(M);
  std::copy(r[i], r[i] + M, rvec[i].begin());
}

If rvec itself and each vector in rvec already has the correct size, then resizing isn’t needed.