C++ boost类库timer测试程序运行时间

#include <Windows.h>
#include <iostream>
#include <boost/timer.hpp>
using namespace boost;
using namespace std;

int main()
{

 timer tm;

 double sum = 0;
 for (int i=0; i<1000000000; i++)
 {
  sum += i;
 }

 cout << sum << "OK" << endl;

 double duration = tm.elapsed();
 cout << duration << endl;
 int wait;
 cin >> wait;
 return 0;
}