Global variables are easy to use.You are right. Neo1 is wrong to say that all functions must return some value. Indeed, Neo1 gave a counterexample in the same post: functions with a return type of void do not return a value. On the other hand, Neo1 also pointed out that your functions are supposed to return a value since you did not specify that their return type was void. Since you do not intend them to return values, you should declare them with a return type of void.
I thought you might say that. Well, I am not making the claim so I do not need to either
So, what claim would you like to make concerning global variables?