4. Introduce a call-by-pointer function with void output. that computes the square of an integer. Please double check the value of the function input before and after function call.

5. Introduce an integer vector. Then introduce a function to reverse this vector. (Do not use reverse library provided by C++.

6. Introduce an integer vector. Then introduce a function to check whether this vector is palindrome. If yes, please return true. If not, please return false.