LinAGPrime-C

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

int main(int argc, char* argv[]) {
    if(argc < 2) {
        fprintf(stderr, "Must specify max, e.g. \"%s 10000000\"\n", argv[0]);
        return -1;
    } else if(argc > 2) {
        fprintf(stderr, "Too many arguments\n");
        return -1;
    }

    const int MAX = atoi(argv[1]); // Programmet hittar all primtal under MAX

    int len_allocated = 8;
    int* primes = malloc(len_allocated * sizeof(int));
    int* primes_square = malloc(len_allocated * sizeof(int));

    if(primes == NULL || primes_square == NULL) {
        fprintf(stderr, "Failed to allocate memory\n");
        exit(EXIT_FAILURE);
    }

    int len = 0;

    int i;
    for(i = 2; i < MAX; i++) {
        int divisible = 0;

        int j;
        for(j = 0; j < len; j++) {
            if(primes_square[j] > i) {
                break;
            }
            if(!(i % primes[j])) {
                divisible = 1;
                break;
            }
        }


        if(!divisible) {
            if(len >= len_allocated) {
                len_allocated *= 2;
                if((primes = realloc(primes, len_allocated * sizeof(int))) == NULL || (primes_square = realloc(primes_square, len_allocated * sizeof(int))) == NULL) {
                    fprintf(stderr, "Failed to allocate memory\n");
                    exit(EXIT_FAILURE);
                }
            }
            primes[len] = i;
            primes_square[len] = i * i;
            len++;
            printf("%d\n", i);
        }
    }

    return 0;
}