Copying step in merge function

Can you please explain why we have copied the elements of temp array in array a in merge function.
If we don’t do that then what will happen?
What is the use of that ?
Will my code still work if I have not done this copying step?

How will you merge sorted subarrays without using auxillary space?
Swapping wont help you can do dry run.

I hope I’ve cleared your doubt. I ask you to please rate your experience here
Your feedback is very important. It helps us improve our platform and hence provide you
the learning experience you deserve.

On the off chance, you still have some questions or not find the answers satisfactory, you may reopen
the doubt.