Getting the exact same results from rand() due to global object being created before main function

Question

I am using rand to get some "random" numbers, on Windows, Visual Studio 2010.

In the main file I've included and and using this:
srand(time(NULL))

And in another file, in the constructor of an object
(object is defined globally, due to its use in OpenGL functions(Init, Render)
I am calling rand() % bound, 10 times and getting the same result, both at my laptop and desktop.

This should be due to the object being created before the seeding of rand from main.

How can I avoid that and keep the object being global?

Answer 1

In the constructor of your global object, do srand(time(NULL)) before using rand. Alternatively, have another non-local object with static storage duration that does srand(time(NULL)). Make sure it is defined in the same translation unit but before your object that uses rand. Non-local objects with static storage duration are initialised in definition order.