Is recursion possible in a static function?

Question

Is it possible to write a recursive static function in the C language?

Answer 1

Yes, and why not?!

Answer 2

Yes. When you apply static to a function, it's not the same as a static variable within a recursive function (which is a problem).

The former simply controls whether the function is visible outside the compilation unit (for the linker, for example).

The latter means that there's only one copy of the variable for all recursion levels rather than one per recursion level, which is usually what's needed.

So:

static unsigned int fact (unsigned int n) {
    if (n == 1U) return 1;
    return n * fact (n-1);
}

is okay, but:

static unsigned int fact (unsigned int n) {
    static unsigned int local_n; // would be fine if not static!
    local_n = n;
    if (local_n == 1U) return 1;
    return local_n * fact (local_n-1);
}

is not, since the static variable will be corrupted.

Answer 3

#include <stdio.h>

static void count_to_five(void)
{
   static int i = 0;

   while (i < 5) {
     i++;
     printf("%d\n", i);
     count_to_five();
   }

  puts("You are seeing this because I counted to five! (did not enter loop)\n");    
  return;
}

int main(void)
{
    count_to_five();
    return 0;
}

So, yes. Note, static storage for i means it retains its value with each call of count_to_five(). However, count_to_five() need not be defined as static.

Its very hard to tell what you're asking.