Question

Let’s say I have this program:

class Foo {
 public:
    unsigned int bar () {
        static unsigned int counter = 0;
        return counter++;
    }
};

int main ()
{
    Foo a;
    Foo b;
}

(Of course this example makes no sense since I’d obviously declare “counter” as a private attribute, but it’s just to illustrate the problem).

I’d like to know how C++ behaves in this kind of situation: will the variable “counter” in the bar() method be the same for every instance?

Answer 1

Yes, counter will be shared across all instances of objects of type Foo in your executable. As long as you’re in a singlethreaded environment, it’ll work as expected as a shared counter.

In a multithreaded environment, you’ll have interesting race conditions to debug :).