Passing vector by reference

Question

Using normal C arrays I\'d do something like that:

void do_something(int el, int **arr)
{
   *arr[0] = el;
   // do something else
}

Now, I

Answer 1

You can pass the container by reference in order to modify it in the function. What other answers haven’t addressed is that std::vector does not have a push_front member function. You can use the insert() member function on vector for O(n) insertion:

void do_something(int el, std::vector &arr){
    arr.insert(arr.begin(), el);
}

Or use std::deque instead for amortised O(1) insertion:

void do_something(int el, std::deque &arr){
    arr.push_front(el);
}