Conclusions of Functions & Pointers in C Programming

From the programs that we discussed here we can draw the following conclusions:

(a)If we want that the value of an actual argument should not get changed in the function being called, pass the actual argument by value.
(b)If we want that the value of an actual argument should get changed in the function being called, pass the actual argument by reference.
(c)If a function is to be made to return more than one value at a time then return these values indirectly by using a call by reference.