How to move std::vector through move semantics

It seems that I cannot completely understand move semantics: I want to fill an std::vector (member of a class) from an external function. Currently, I have something like:

void fillVector(MyClass & myclass) {
    std::vector<int> vec;
    /* Filling vec */
    // ...
    myclass.setVector(vec);
}

class MyClass {
    public:
         setVector(const std::vector<int> & v) { v_ = v;}
    private:
         std::vector<int> v_;
};

int main() {
    MyClass myclass;
    fillVector(myclass);
    /* Use myclass.v_ somehow */.
}

I had this code for a long time, and it works fine. Now, I cannot understand how it works since I am asigning a reference to a vector which will be destroyed. My questions are:

1. How is this code able to work?


2. What is the best way to implement fillVector and MyClass::setVector()? I think that can be done with move semantics but I cannot figure out how.

Thank you!