判断是不是素数

#include "stdafx.h"

int isPrime(long n)
{
    long a;
    a = 2;
    while (a < n)
    {
        if (n%a == 0)
            break;
        a++;
    }
    if (a == n)
        return 1;
    else
        return 0;
}

int main()
{
    //while (scanf_s("%ld", &n) != EOF)
    //{
    //}
    int num = 0;
    long length = 100;
    for (long i = 1; i < length; i++)
    {
        if (isPrime(i) == 1)
        {
            printf("%d ", i);
            num++;
        }
    }
    printf("
在%d的数字中有%d个素数如上
", length, num);
    return 0;
}