Question

I was told that a function defined as static in one .c file is not accessible from other files. But in the following program, I can access the static void show() function from another file. Is my understanding of static functions in C wrong?

a.h (first file):

static void show()
{
printf("I am in static show function in a.c");
}

b.c (another file):

#include"a.h"
void main()
{
show();
}

Answer 1

Remember that #includes work by copy-and-pasting the content of the included file. So in your example, after the #include has been processed, you get this:

static void show()
{
printf("I am in static show function in a.c");
}

void main()
{
show();
}

So clearly main can see show.¹

The solution is to not #include .c files. In general, you should only #include header (.h) files. Your static functions shouldn’t be declared or defined in the header file, so main will not be able to see it.

---

_{1. However, you now actually have two definitions of the show function, one in a.c and one in b.c. For static functions, this isn’t a problem, but for non-static functions you would get a linker error.}