Fibonacci advanced version by Alejandro Piqueras

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

int fibonacci(int n) {
    // Exit the program if n is negative
    if (0 > n) exit(1);
    switch (n) {
        // Special cases n = 0 and n = 1
        case 0:
        case 1:
            return n;
            break;
        default:
            // Fibonacci formula for n > 1
            return fibonacci(n - 1) + fibonacci(n - 2);
    }
}

int main() {
    // Loop for printing the first 6 numbers of the succession
    for (int i = 0; 6 > i; i++) {
        printf("%i ", fibonacci(i));
    }
    printf("\n");
    return 0;
}