should assign `nullptr` to `std::unique_ptr` before assigning a new value to it?

Question

#include <iostream>
#include <memory>
using namespace std;

int main() {
    std::unique_ptr<int> ptrA = std::make_unique<int>(10);

    ptrA = std::make_unique<int>(20); // case I

    return 0;
}


#include <iostream>
#include <memory>
using namespace std;

int main() {
    std::unique_ptr<int> ptrA = std::make_unique<int>(10);

    ptrA = nullptr;                  // case II or ptrA.reset()
    ptrA = std::make_unique<int>(20);

    return 0;
}

I have seen many people use Case II. However, std::unique_ptr is a smart pointer, I don't think we should assign either nullptr or call reset before reassigning a new value to it.

Please correct me if I am wrong here.

Answer 1

Assigning nullptr before assigning a new value is pointless.