Vector code for C++ to arrange negative numbers before positive numbers.

So, you show no attempt to solve the problem yourself, you have no question, you just want us to do your HomeWork.
HomeWork problems are simplified versions of the kind of problems you will have to solve in real life, their purpose is learning and practicing.
We do not do your HomeWork.
HomeWork is not set to test your skills at begging other people to do your work, it is set to make you think and to help your teacher to check your understanding of the courses you have taken and also the problems you have at applying them.
Any failure of you will help your teacher spot your weaknesses and set remedial actions.
Any failure of you will help you to learn what works and what don't, it is called 'trial and error' learning.
So, give it a try, reread your lessons and start working. If you are stuck on a specific problem, show your code and explain this exact problem, we might help.

As programmer, your job is to create algorithms that solve specific problems and you can't rely on someone else to eternally do it for you, so there is a time where you will have to learn how to. And the sooner, the better.
When you just ask for the solution, it is like trying to learn to drive a car by having someone else training.
Creating an algorithm is basically finding the maths and make necessary adaptation to fit your actual problem.

Quote:

Do not write a
MAIN FUNCTION.

Advice: write a main function, so you can compile the code and check what it does.
the main function call 'arrangeVector' with some sample data.
Then remove the main function before submitting.

This homework is so simple. Think about tiny steps like

1. find elements which are less than zero
2. move the element to the start of the vector

Learn from some vector tutorial.

tip: make a sample project in which you include your solution code file.

Suppose you make a loop over vector items.
At iteration i, if v[i] is negative then continue the iteration.
On the other hand, if v[i] is not-negative then perform another loop (starting with j = i + 1) in order to find a v[j] negative: if such item is not found then you've finished. On the other hand, if such item is found swap v[i] with v[j] and continue the outer loop iteration.