Dividing code

Hi,

After a year of using c# and gaining object programming experience I decided to improve my c++ skills.

What I particularly liked about c# was the way of dividing source into different files. It all just worked fine .

Now I want to do the same using c++. I'm going to create an sdl game, and to avoid a mess in code, I want to divide it all at least into the following sections: main, load_data, update, draw.

The problem is that functions in all of those sections will use the same data and probably will use the same classes/structures.

1)I tried myself divide the code, but it doesn't work, and below you can see an example, of what I tried:

main.cpp

Code:

#include "declarations.h"
#include "load_resources.cpp"

Resources res;

int main ( int argc, char** argv )
{
    load(res);

    return 0;
}
declarations.h
 #ifndef DECLARATIONS_H_INCLUDED
#define DECLARATIONS_H_INCLUDED

struct Resources
{
    int a;
    int b;

};

bool load(Resources &res);

#endif // DECLARATIONS_H_INCLUDED

load_resources.cpp
 #include "declarations.h"

bool load(Resources &res)
{
    return true;
}

multiple definition of `load(Resources&)'|


2) The other problem is that every section should have access to the same data. What's, the best way for it? In c# I just had to create a public static call. In c++ - I have no idea.

Help me please.
Bye