Thread: Global Structure

I am desperately stuck please help.....

I am trying to use a structure which can be accessed and changed by my main c file as well as some header files which I am creating to go with it.

I have tried a few methods, but have been unsuccessful.

My last atempt took the following form:


The main file included two header files, one header file which held the structure definition and declared the array of structures, the other held a function which added data elements to the structure. The main file also needs to be able to add data and read data to and from the structure.

For example:

main.c
------------------

Code:

#include <header1.h>
#include <header2.h>

int main(void){
      
MyFunction();

}

header1.h
-------------------

Code:

struct Data{
int data1;
char data2[20];
};

struct Data structArray[20];

header2.h
------------------

Code:

#include <header1.h>

void MyFunction();

void MyFunction(){

structArray[0].data1 = 2;
structArray[0].data2[0] = 's';
}

Any help is much appreciated, thanks in advance

Ok, I have done that.... that didn't appear to have any effect. I think my compliler must have ignored that I had written in those chevrons because it was finding the structure definition from the header file without any problem.

The error that I am being given when I try to compile is:

redefinition of 'struct mystructure'

For reference I am using Dev C++ 4.9.9.1

Don't declare global variables or functions in header files.

Header files should ONLY contain definitions of data types,
function prototypes and C preprocessor commands.

ok... so what is the best way to have a structure that I can access in my main program and have functions in header files that use the structure??

I have been experimenting with different methods, but not yet found one that works.

One method I was trying is to have the structure declared in the main *. file. But I couldn't figure out how to define the pointer in the function prototype?? Everything I was trying failed. I figured that the header file must need access to the structure definition to know what kind of data and data sizes it is pointing to. This is what led me to define the structure in a header file which both could access.

Many thanks for the help so far

Thanks so much... that worked a treat.

I shall be sure to read the FAQ.