Function to make a list of primes.

makeprimes.c

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

inline
int isPrime(int check, int *primes) {
	for (; (*primes * *primes) < check; primes++) 
		if (check % *primes == 0) return 0;
	return 1;
}

int *MakePrimes(int num) {
	int *primes = malloc(4 * num);
	int count = 1;
	int curNum = 3; //Start searching at 3
	primes[0] = 2; //Set our first prime to 2
	
	for (;count < num; curNum++) {
		if (isPrime(curNum, primes)) {
			primes[count++] = curNum;
		}
	}
	return primes;
}


int main() {
	int *p = MakePrimes(40000);
	int i = 0;
	for (; i < 40; i++) {
		printf("%d\n",p[i]);
	}
	return 0;
}