第三部分（四）：素数筛子算法

2021/11/27

int is_prime(int a)
{
	for (int i = 2; i * i < a; i++)
	{
		if (a % i == 0)
			return 0;
	}
	return 1;
}

#include
main()
{
	int n;
	printf("please input a number,system will return the number of primes between 2 and it:n");
	scanf_s("%d", &n);
	for (int i = 2; i <= n; i++)
	{
		if (is_prime(i))
			printf("%d ", i);
	}
}