C++中如何计算程序运行的时间

C++中计算程序运行的时间，代码如下：

#include<iostream>#include<ctime>using namespace std; int main(){    clock_t start,finish;    start=clock();         cout << "HW .... " << endl;     finish=clock();     cout << finish-start   << "/" << CLOCKS_PER_SEC  << " (s) "<< endl;         return 0;}