Structure in header won't declare.

I'm trying to create a game for my own entertainement, and for some reason, it gives me an error.

I'm posting the entire thing so far.

Main.cpp

Code:

---

//Inculde the main header file
#include "main.h"
//Incude the global variable allocation header
#include "globalvar.h"

//Game initialization function. Gets the game ready to run.
int functMainStartGame()
{
    global.exitgame = false;
}

//Step function, for the main program. All main program code executed here.
int functMainStep()
{
    //while(global.exitgame == false)
    //{
    ////put code for game here.
    //}
   
}

//Game ending function. Ends classes, closes rendering system, ect.
int functMainEndGame()
{
}

int main()
      {
      functMainStartGame();
      functMainStep();
      functMainEndGame();
      return 0;
      }

---

main.h

Code:

---

//todo: Add header files to declare here.

//create global variable container.

struct globalStruct
{
      int exitgame;
      int *entities[0];
      int numbofentities;
};
extern globalStruct global;//declare it

---

And globalvar.h

Code:

---

globalStruct global;

---

EDIT: Oh, entites.cpp too.

Code:

---

#include "globalvar.h"

class entMain
{
      public:
            int myx;
            int myy;
            float xspeed;
            float yspeed;
      entMain(int x, int y)
      {
      global.instances[global.numbofentities] = &this;
      global.numbofentities += 1;
      }
      ~entMain()
      {
      }
      int entRepeatMe()
      {
      }
};

---

http://img170.imageshack.us/img170/9614/whatdk4.png

I'm,using Dev C++ v4.9.9.2.

Please note I am just beginning at C++, so it may have been something simple.

Thanks

-CornJer

It helps to post the exact error and the line on which it occured; however, I can guess from your title what the error is.

What's this supposed to do? Is it just a template?

Code:

---

int *entities[0];

---

Are you getting a linker error to the effect that you have two variables of the same name?

The error is in the link.

http://img170.imageshack.us/img170/9614/whatdk4.png

Well, entries.cpp includes globalvar.h but not main.h; it tries to declare a globalStruct without knowing what a globalStruct is. You need to have the definition of the structure in entries.cpp.

[edit]
Think about it; after the preprocessor does its job, entries.cpp looks like this:

Code:

---

// What's a globalStruct?
globalStruct global; // was #include "globalvar.h"

class entMain
{
      public:

---

You were very thourough in your question, by the way. I'm impressed.
[/edit]

Thanks!

But now it gives me this error as well:

http://img135.imageshack.us/img135/1672/error2rk2.png

globalStruct doesn't appear to have an instances member; perhaps you meant entities?

Code:

---

      global.instances[global.numbofentities] = &this;

---

That line... first: global has no member named instances. The closest thing is probably entities. Second, (the error) is that you are saying "&this" - take the address of 'this'. (I cannot imagine what the answer would be, can you?) The variable 'this' is a pointer to the class who's member is being called, and is (in this case) of type entMain *.

Yeah, sorry, meant entities.

So if the keyword "this" doesn't point to an instance of class's address, what does?

It does point to the instance of a class; but it's a pointer already. &this will give you **class_type.

Odd. If thats so, why does it give me this error?

Code:

---

global.entities[global.numbofentities] = this;

---

http://img100.imageshack.us/img100/760/error3ti9.png

Sorry to keep pestering you. ;)

You're trying to assign a class to an

Code:

---

int *entities[0];

---

Not good. Declare it like so:

Code:

---

entMain *entities[whatever];

---

You may need a forward declaration before the structure:

Code:

---

class entMain;

---

Excellent! It runs perfectly now!

Thanks a bundle!

As a note, making an array of pointers to objects is not very good practice, for 2 reasons:

1. No way to automatically deallocate the objects,
2. No way to automatically allocate/deallocate the array.

I'd say you should consider a boost::ptr_vector<> for this job. It will automatically call destructors for your objects as they're removed, and it will automatically call destructors when your program ends.

You do know you can copy and paste errors from dev-c++, you don't have to keep posting images.
Just select the "Compile Log" tab and you can just select the text.