c++中统计时间的几种方法

方法1

#include <ctime>
clock_t  start = clock();
// do something ...
clock_t end = clock();
cout<<"花费了："<<(double)(end-start)/CLOCK_PER_SEC<<"秒"<<endl;

方法2

using namespace chrono;
auto start = system_clock::now();
// do something ...
auto end = system_clock::now();
auto duration = duration_cast<milliseconds>(end - start);
cout<<"花费了："<<duration.count() * 1.0 / 1000<<"秒"<<endl;

方法3

#include <sys/time.h>
struct timeval  start, end;
gettimeofday(&start, NULL);
// do something ...
gettimeofday(&end, NULL);
auto usedTime = (end.tv_sec - start.tv_sec) * 1000.0 + (end.tv_usec - start.tv_usec) / 1000.0;
cout<<"花费了"<<usedTime<<"ms"<<endl;