C++ problem

Write a program that uses multiple functions; have a function to calculate the surface area of a rectangular parallelepiped (Call it calculateSurfaceArea) and the other function to calculate volume of a rectangular parallelepiped (Call it calculateVolume) (see drawing below), given the length, height and width. Use a single function to input the length, height and width into the program. Call it getlnput and use pass by reference in this function. Ensure, in that function, that all inputs are greater than zero. Write a function that outputs the length, height, width and surface area and volume of the rectangular parallelepiped