Work with a std::vector that matches the memory of an array of double

I am trying to connect to existing codes - one being in c, the other one in cpp. The cpp code uses std::vector whereas the other one is based on arrays of double. I would like to pass arrays of double from the c code, perform operations on std::vector's in the cpp one and eventually reflect these operations on the array of double. Is it possible to create a std::vector that matches the memory occupied by the array of double? Based on what I have found on the website, I have tried several options, but they all involve the creation of a new vector and a copy of that vector onto the array of double... For instance: void fcn(double* a, int sizeofa) { std::vector<double> vect_a; vect_a.assign(a, a + sizeofa); // operations on vect_a for (int i=0;i<sizeofa;i++) { a[i] = vect_a[i]; } } Thank you much for your help!