Thread: Difference between Staic and Const Keywords

Const just says this variable's value won't change, and so trying to change it will yield a compile error.
Static can mean different things depending on where it's used. If used in a function, it will create a variable which retains its value between function calls. Its lifetime is from the beginning of the program to the end.
On a global level, it has a different meaning, though. I'm sure someone else can fill in on that, but I'd just avoid it. It's not really necessary.

A const is a value which does not change.

Code:

const int x = 5;

You cannot change the value of x without casting it non-const.

A static variable maintains it's value between function calls:

Code:

void test() {
     static int x = 5;
     x++;
     printf("%d\n",x);
}

The first time you call test(), x will be 6. Next time it will be 7, and so on. Ie, because it is static, it is initialized only once during execution (sort of like a global, for which they are useful replacements).

A static function limits the declaration to file scope:

Code:

static void test();

This will not be accessible to executables which link to the executable compiled from this file*, which can help prevent namespace collisions (at least, I believe that is the purpose). I think this is also the meaning Elysia has in mind WRT to "global" static variables, which would be similarly limited in scope to a single file.

* or from one file to the next if compiled together