#include<iostream>
using namespace std;
// 定义一个判断质数的函数，用return返回判断结果
bool isPrime(int num)
{
int i = 2;
while (i < num)
{
if (num % i == 0) return false;
++i;
}
return true;
}
int main()
{
cout << "请输入一个自然数（不超过20亿）：" << endl;
int num;
cin >> num;
if (isPrime(num))
{
cout << num << "是质数！" << endl;
}
else
{
cout << num << "不是质数！" << endl;
}
cout << "\n=========================\n" << endl;
cout << "0 ~ 100 内的质数有：" << endl;
for (int i = 2; i <= 100; i++)
{
if (isPrime(i))
cout << i << "\t";
}
cout << endl;
cin.get();
cin.get();
}