Doing Fizz Buzz with a State Machine

fizzbuzz_machine.c

/*
 * Brian Chrzanowski
 * Mon May 06, 2019 23:41
 *
 * This was a meme. A friend of mine thought about how you could do fizz-buzz
 * as a 15(ish) state machine.
 *
 * I think my thing is closer to a circular linked list with function pointers,
 * but that's whatever.
 */

#include <stdio.h>
#include <stdlib.h>

#define USAGE "%s <num>\n"

struct state_t {
	void (*func) (char *);
	struct state_t *next;
};

void fizz(char *s)
{
	printf("fizz\n");
}

void buzz(char *s)
{
	printf("buzz\n");
}

void fizzbuzz(char *s)
{
	printf("fizz buzz\n");
}

void pnum(char *s)
{
	printf("%s\n", s);
}

int main(int argc, char **argv)
{
	struct state_t *curr;
	struct state_t machine[15];
	int i, c, maxnum;
	char buf[32];

	if (argc < 2) {
		fprintf(stderr, USAGE, argv[0]);
		return 1;
	}

	maxnum = atoi(argv[1]);

	// push states onto the machine
	for (curr = machine, i = 0, c = 1; i < 15; i++, c++, curr++) {
		curr->next = curr + 1;
		if (c % 3 == 0 && c % 5 == 0) {
			curr->func = fizzbuzz;
		} else if (c % 5 == 0) {
			curr->func = buzz;
		} else if (c % 3 == 0) {
			curr->func = fizz;
		} else {
			curr->func = pnum;
		}
	}

	// hook up the link to the first state, to execute "forever"
	curr--;
	curr->next = &machine[0];

	// execute the machine
	for (curr = machine, i = 1; i < maxnum; i++, curr = curr->next) {
		snprintf(buf, sizeof(buf), "%d", i);
		printf("%d\t", i);
		curr->func(buf);
	}

	return 0;
}