C dilinde yardım (soru)

#include <stdio.h>
#include <math.h>
int fibonacci(int nth);
void isPrime(int number);

int main()
{
    int i;
    int n = 10;
    for(i = 1; i < n; ++i){
        int fib= fibonacci(i);
        isPrime(fib);
    }
    return 0;
}


int fibonacci(int nth) {
    if (nth <= 1) 
        return nth; 
    return fibonacci(nth - 1) + fibonacci(nth - 2); 
}

void isPrime(int num) {
   int i, p = 0;
   for(i=1; i<=num; i++)
   {
      if(num%i==0)
      {
         p++;
      }
   }
   if(p==2)
   {
      printf("%d is a prime number 
 ",num);
   }
   else
   {
      printf("%d is not a prime number 
 ",num);
   }
}