质数测试（关于强制转换）

//prime.cpp

#include
#include
using namespace std;

int main()
{
 int n;       
 int i;
 double m;
 int is_prime;

 is_prime = true;

 cout << "Enter a number and press ENTER:" << endl;
 cin >> n;

 m = sqrt(static_cast < double > ( n ));    // 类型转换
 i = 2;
 while ( i<=m )
 {
  if ( n % i == 0 )
  {
   is_prime = false;
   break;
  }
  i++;
 }

 if ( is_prime )
  {
   cout << "Number is prime!" << endl;
  }
 else
  {
   cout << "Number isn't prime!" << endl;
  }

 return 0;
 cin.get();
}