fibonacci.c

#include <stdio.h>
#include <time.h>
#include <sys/time.h>

int fibonacci(int n);

int main() {
	clock_t begin, end;
	float z;
	int a;
	begin = clock();
	a = fibonacci(30);
	end = clock();
	z = (end - begin)/CLOCKS_PER_SEC;
	printf("Fibonacci number(30): (%d) in %d s = %d / %d s", a, z, (end - begin), CLOCKS_PER_SEC);
}

int fibonacci(int n) {
	if (n > 2) 
		return fibonacci(n-2) + fibonacci(n-1);
	if (n == 2 || n == 1) 
		return 1;
	return 0;
}

Simple demonstration to calculate the n-th element of a fibonacci sequence in C using recursion.