计算程序运行的时间一个函数

#include<iostream>
#include<time.h>
using namespace std;
int main()
{
double n;
while (cin >> n)
{
int k = 0;
for (int i = 0; i < n; i++)
{
k++;
}
cout << k << endl;
cout << "time is" << double(clock()) / CLOCKS_PER_SEC<<endl;
}
return 0;
}