define array length struct with global constant from other file - c

Question

In my model I have quite some parameters that are used by a lot of different functions.
To make changing settings easy, I want to use one file for all my paramaters, keeping it sepperate from any of the "real programming".
That file is called parameters.c
In it, all parameters are defined like:
#define N 1000
#define T 1373
In a different c file (MyLib.c), I create a struct type:
typedef struct Model{
struct Element el[N];
};
both files are included in my main script using:
#include "parameters.c"
#include "MyLib.c"
The project can not be build this way. However, if I move the line
#define N 1000
from parameters.c to MyLib.c, it works.
I could just create the struct to have an array that is larger than any N value I'd use, but that doesn't seem like the correct way to do it.
Is there a correct way to implement this, or would I indeed have to create the large array? (in the comments it was said the definition of correct is too broad. In this instance I mean memory efficient. I don't want to allocate a much larger chunck of memory than I need to.)
Thanks in advance.

Answer 1

Is there a correct way to implement this
You library may look like this:
// parameters.h
#ifndef PARAMETERS_H_
#define PARAMETERS_H_
// documentation
#define PARAMETERS_COUNT_OF_ELEMENTS 1000
// this parameters does that and that
#define PARAMETERS_DESCRIPTIVE_NAME 1373
// ^^^^^^^^^^^ - consistent namespace naming
#endif
// mylib.h - safe yourself trouble and DoN'T mIx UppErCaSe with lOwErcAsE
// escapecially in header names
// subjectively, I do not like pascal case - snake case rule them all!
#ifndef MYLIB_H_
#define MYLIB_H_
#include "parameters.h"
#include "element.h" // for struct element
/// This structure represents a model in our library.
struct mylib_model {
// ^^^^^^ - consistent namespace naming
/// These are super important elements we deeply care about.
struct element el[PARAMETERS_COUNT_OF_ELEMENTS];
};
/**
* #brief this function does that and that
* #return 0 on success, otherwise error
*
* Write documentation keeping consistent style, for example
* use doxygen.
*/
int mylib_do_something(struct mylib_model *the_model);
#endif
// mylib.c
#include "mylib.h"
int mylib_do_something(struct mylib_model *t) {
// do something here
// return 0 on success, otherwise document error codes, or use the ones from errno.h
return 0;
}
// main.c
#include "mylib.h"
int main() {
struct mylib_model model = {0};
int err = mylib_do_something(&model);
if (err != 0) { abort(); }
return 0;
}
Your parmeters.h is very similar to the way autoconf projects generate config.h present in many GNU projects. Many projects use a configuration file, sometimes generate automatically by a build system. Nowadays if choosing build automation software I would recommend cmake. Other links: kernel coding style and google coding style.