#include <iostream>

using namespace std;

int set [1000000];

int main (){

    for (int i=0; i<1000000; i++){
        set [i] = 0;
    }
    int set_size= 1000;
    set [set_size];
    set [0] = 2;
    set [1] = 3;
    int Ps = 0;
    int last = 2;

    cout << 2 << " " << 3 << " ";

    for (int n=1; n<10000; n++){
        int t = 0;
        Ps = (n%2)+1+(3*n);
        for (int i=0; i==i; i++){
            if (set [i] == 0) break;
            if (Ps%set[i]==0){
                t=1;
                break;
            }
        }
        if (t==0){
            cout << Ps << " ";
            set [last] = Ps;
            last++;
        }
    }
    //cout << last << endl;


    cout << endl;

    system ("pause");
    return 0;
}

#include<iostream>
using namespace std;

void main()
{
    int num,i,j,prime;
    cout<<"Enter the upper limit :";
    cin>>num;

    cout<<"Prime numbers till "<<num<<" are :2, ";

    for(i=3;i<=num;i++)
    {
        prime=1;
        for(j=2;j<i;j++)
        {
            if(i%j==0)
            {
                prime=0;
                break;
            }
        }

        if(prime==1)
            cout<<i<<", ";

    }
}

一个非常快速的Atkin Sieve的实现是Dan Bernstein的primegen。这个筛子比埃拉托色尼的筛子更有效率。他的页面有一些基准测试信息。

如果它必须非常快，你可以包括一个质数列表: http://www.bigprimes.net/archive/prime/

如果你只想知道某个数是不是质数，维基百科上列出了各种质数判别法。它们可能是确定大数是否为质数的最快方法，特别是因为它们可以告诉你一个数是否为质数。

Rabin-Miller是一个标准的概率质数检验。(你运行K次，输入数字要么肯定是合数，要么可能是素数，误差概率为4-K。(经过几百次迭代，它几乎肯定会告诉你真相)

拉宾·米勒有一个非概率(确定性)的变体。

The Great Internet Mersenne Prime Search (GIMPS) which has found the world's record for largest proven prime (274,207,281 - 1 as of June 2017), uses several algorithms, but these are primes in special forms. However the GIMPS page above does include some general deterministic primality tests. They appear to indicate that which algorithm is "fastest" depends upon the size of the number to be tested. If your number fits in 64 bits then you probably shouldn't use a method intended to work on primes of several million digits.

I know it's somewhat later, but this could be useful to people arriving here from searches. Anyway, here's some JavaScript that relies on the fact that only prime factors need to be tested, so the earlier primes generated by the code are re-used as test factors for later ones. Of course, all even and mod 5 values are filtered out first. The result will be in the array P, and this code can crunch 10 million primes in under 1.5 seconds on an i7 PC (or 100 million in about 20). Rewritten in C it should be very fast.

var P = [1, 2], j, k, l = 3

for (k = 3 ; k < 10000000 ; k += 2)
{
  loop: if (++l < 5)
  {
    for (j = 2 ; P[j] <= Math.sqrt(k) ; ++j)
      if (k % P[j] == 0) break loop

    P[P.length] = k
  }
  else l = 0
}