The challenge is to calculate the sum of the first 1000 primes. The code applies a sieve thanks to past answer, here, and works but I wonder about the flexibility of this solution.

#include <stdio.h>
unsigned long compute_sum_of_primes(int primes_needed) {
 int sieve_size = 20 * primes_needed;
 int sieve[sieve_size];
 unsigned long sum = 0;
 for (int i = 0; i < sieve_size; i++) {
 sieve[i] = 1;
 }
 for (int prime = 2; primes_needed > 0; prime++) {
 if (sieve[prime]) {
 sum += prime;
 primes_needed--;
 for (int composite = prime + prime; composite < sieve_size; composite += prime) {
 sieve[composite] = 0;
 }
 }
 }
 return sum;
}
int main() {
 unsigned long sum_of_primes = compute_sum_of_primes(1000);
 printf("%lu\n", sum_of_primes);
}

The challenge is to calculate the sum of the first 1000 primes. The code applies a sieve thanks to past answer, here, and works but I wonder about the flexibility of this solution.

#include <stdio.h>
unsigned long compute_sum_of_primes(int primes_needed) {
 int sieve_size = 20 * primes_needed;
 int sieve[sieve_size];
 unsigned long sum = 0;
 for (int i = 0; i < sieve_size; i++) {
 sieve[i] = 1;
 }
 for (int prime = 2; primes_needed > 0; prime++) {
 if (sieve[prime]) {
 sum += prime;
 primes_needed--;
 for (int composite = prime + prime; composite < sieve_size; composite += prime) {
 sieve[composite] = 0;
 }
 }
 }
 return sum;
}
int main() {
 unsigned long sum_of_primes = compute_sum_of_primes(1000);
 printf("%lu\n", sum_of_primes);
}