计算程序运行时间

#include <iostream>
#include <time.h>
int main(void)
{
int sum = 0;
time_t t,t1;        time(&t);        //t = time(NULL);
std::cout<<ctime(&t);        //单位为秒

int star = clock();                //单位毫秒
for (int i=1; i <=10000; ++i)
{
sum = sum+i;
}
std::cout<<sum<<std::endl;
int stop = clock();
std::cout<<stop - star<<"毫秒"<<std::endl;
time(&t1);
int t3 = t1-t;
std::cout<<t3<<" 秒"<<std::endl;
std::cout<<ctime(&t1);
system("pause");
return 0;
}