primes.c

#include <stdio.h>

#define LEN 1200000000

char nums[LEN];

int main() {
    nums[0] = 1;
    nums[1] = 1;

    long primes_count = 0;
    long last_prime = -1;

    long i = 2;
    while( i < LEN ) {
        if( i < 100 || (i < 1000000 && (i % 1000) == 0) || i % 1000000 == 0) {
            printf("%ld\n", i);
        }
        if( nums[i] == 0 ) {
            primes_count += 1;
            last_prime = i;
            long j = 2 * i;
            while(j < LEN) {
                nums[j] = 1;
                j += i;
            }
        }
        i += 1;
    }

    printf("last_prime=%ld, primes_count=%ld\n", last_prime, primes_count);

    return 0;
}

primes.py

#!/usr/bin/python3
import math

LEN=1200000000

nums = bytearray(LEN)

nums[0] = 1
nums[1] = 1

primes_count = 0
last_prime = None

i = 2
while i < LEN:
    if i < 100 or (i < 1000000 and i % 1000 == 0) or i % 1000000 == 0:
        print(i)
    if nums[i] == 0:
        primes_count += 1
        last_prime = i
        j = 2 * i
        while j < LEN:
            nums[j] = 1
            j += i
    i += 1

print(f"{last_prime=}, {primes_count=}")