Question

I’m a new C programmer, so this is a pretty basic question. What is the preferred approach to organizing ANSI C files in a project? I have about a dozen .c files each with their own .h file to hold local declarations, enums, etc. But I also have quite a few global parameters such as…

float LandingAltitudeList[2][17] = {
    // P100
    {12,-1000,0,1000,2000,3000,4000,5000,6000,7000,8000,9000,10000},
    // P300
   {16,-1000,0,1000,2000,3000,4000,5000,6000,7000,8000,9000,10000,1000,12000,13000,14000}  };

enum PType {P100,P300};
enum Boolean {No=0,Yes=1,Off=0,On=1};

In addition, I have a number of global variables such as…

float Alt_min = LandingAltitudeList[PhenomType][1];
int Max = LandingAltitudeList[PhenomType][0];
float Alt_max = LandingAltitudeList[PhenomType][Max];

which I calculate just once, but use throughout the project. These need to be in a function in order to work.

How should I organize my files to handle these global parameters? Many thanks.

Answer 1

One option is to declare these variables in a header file. It would be probably more appropriate to make the variables themselves invisible and to declare access functions to interface them. Consider the following example:

/* in access.h */
int access_secret();
...

/* in access.c */

/* the private variable */
static int very_secret;

void calculate_secret() {
    very_secret = 42;
}

void access_secret() {
    return very_secret;
}

calculate_secret is called just once, when the module is initialized, and access_secret, when the variable value is needed. It is easy to enhance the system by adding array index parameter for arrays.