Global Variables

[xanmas]

Hi,

I was wondering, what are the disadvantages of using global variables? How does c++ keep track of them, etc.

Also, is there any chance that global variables can change without something acting on them?

Is it best practice to avoid globals?

[firedraco]

The disadvantages is that you cannot re-use the same variable name anywhere, so if you have a global named "position", you cannot use "position" anywhere else even if it would make sense. Yes, it is good practice to avoid globals, generally having a lot of globals means you are not implementing OO correctly.

[Bazzy]

If you declare a global it is possible to have a local with the same name:

int n;//global

void f()
{
    int n;//local
    n = 5; //local
    ::n = 5; //global
}

[Zaita]

I was wondering, what are the disadvantages of using global variables? How does c++ keep track of them, etc

Disadvantage is you cannot encapsulate them. So it's hard to put validate the values that might get assigned to them.

If your working on multi-developer projects, this becomes important because you don't want the other developers to mis-use your variable unknowingly.

Also, is there any chance that global variables can change without something acting on them?

No.

Is it best practice to avoid globals?

In Object-orientated development, yes. Because you cannot encapsulate them.

In procedural programming (non-OOD), global variables are ok. But are still typically scoped only to a file level.