Question

Suppose we have an array say:

int arr[1000];

and I have a function that works on that array say:

void Func(void);

Why would there ever be a need to pass by reference (by changing the void), when I can have arr[1000] as an external variable outside main()?

1. What is the difference?Is there any difference?
2. Why do people prefer passing by reference rather than making it external? (I myself think that making it external is easier).

Answer 1

I think you’re asking if global variables are bad. Quoting an excellent answer:

The problem with global variables is
that since every function has access
to these, it becomes increasingly hard
to figure out which functions actually
read and write these variables.

To understand how the application
works, you pretty much have to take
into account every function which
modifies the global state. That can be
done, but as the application grows it
will get harder to the point of being
virtually impossible (or at least a
complete waste of time).

If you don’t rely on global variables,
you can pass state around between
different functions as needed. That
way you stand a much better chance of
understanding what each function does,
as you don’t need to take the global
state into account.