Struct Problem

I'm having a problem with a structure. I declare a structure in the file "Config.c" like this

Code:

---

struct setting{
      int ScreenWidth;
      int ScreenHeight;
};
struct setting *Settings;

---

Then I use this function to set values for ScreenHeight and ScreenWidth

Code:

---

InitSettings(){
    Settings = calloc(1,sizeof(struct setting));
    Settings->ScreenWidth = 1024;
    Settings->ScreenHeight = 768;
}

---

Then I want to accses the struct from another file.

Code:

---

extern struct setting *Settings;

InitGUI(){
    int GameWindowLeft;
    GameWindowLeft = Settings->ScreenWidth - 320;
}

---

The problem is that I get this error message "dereferencing pointer to incomplete type "

Is the structure definition visible in the file that produces the error? Is this part in a header?

Code:

---

struct setting{
      int ScreenWidth;
      int ScreenHeight;
};

---

No the definition is in the file "config.h" and the file that produces the error is "Video.c".

Did you include "config.h" in "Video.c"? I'm guessing you have to do this because an extern isn't enough, since you're accessing one of the data members.

It works!!! I didn't have a clue that you had to include the header file when accsessing an external structure. I will remember that, thank you! :)

You have to tell the compiler what a user-defined data type "looks" like so that it "knows" whether you are using it correctly.