header files & multiple declarations

[Blessman11]

hi

I've already put an "#ifndef" guard in my header file yet it still tells me that my declared objects(which I need globally) "are declared already".

Do I need to stick them in a .cpp file and if so, how can I access them? Would it work if I did?

[Blessman11]

When I declare my objects in a .cpp file it tells me that I can't access them anywhere else. I'm really in a dilema over this. I need my objects to be global across multiple .cpp files yet I dont want the "are declared already" message.

[firedraco]

Declare them as extern in some header file that is included by everyone that needs them, then make them not extern in one of your .cpp files.

[Blessman11]

what does "extern" do? Would it help me or what can instead?

[firedraco]

Extern basically tells the compiler "This variable exists somewhere else." It's basically the same as a function prototype, but for variable definitions.

[Blessman11]

thanks, extern did the trick. Today is the first time I've learnt and appreciated its meaning