How to change a particular element of a C++ STL vector

Question

vector<int> l;
for(int i=1;i<=10;i++){
   l.push_back(i);
}

Now, for example, how do I change the 5th element of the vector to -1?

I tried l.assign(4, -1); It is not behaving as expected. None of the other vector methods seem to fit.

I have used vector as I need random access functionality in my code (using l.at(i)).

Answer 1

at and operator[] both return a reference to the indexed element, so you can simply use:

l.at(4) = -1;

or

l[4] = -1;

Answer 2

This should do it:

l[4] = -1

Answer 3

You can use the subscript operator

l[4] = -1