bitset查找质数

#include <iostream>
#include <cmath>
#include <bitset>

using namespace std;

int main ()

{
	int const max_number(1000000);
	int const max_test((int)sqrt((double)max_number));  // sqrt 是标准库函数cmath的头文件，sqrt是double类型的，
	bitset<max_number> numbers;  // 101个0，
	numbers.set();       //101个1，
	numbers[1] = 0;
	for(int i(1); i != max_test; ++i)  
	{
		if(numbers[i]){
		//筛掉倍数，
			for(int j(i*i); j < max_number; j += i)   //j(i*i)是从i的平方开始，
			{
                 numbers[j] = 0;
			}
		}
	}
             cout << "the number of primes less than " << max_number + 1
				 << " is " << numbers.count() << ".\n\n";
			 for(int i(1); i != max_number + 1; ++i)
			 {
				 if(numbers[i]) 
					 cout << i << ", ";
			 }
                cout << endl; //输出是1000000内的所有质数，

	return 0;
}