Windows 中 C++ 测量时间的 N 种方法

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std::time_t time( std::time_t* arg );

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#include <windows.h>

#include <ctime>
#include <iostream>
using namespace std;
int main() {
  time_t res_1 = time(nullptr);

  Sleep(1000);  // do some stuff...

  time_t res_2 = time(nullptr);

  cout << res_1 << endl;
  cout << asctime(localtime(&res_1)) << endl;
  cout << res_2 - res_1 << 's' << endl;
  return 0;
}

/* 输出结果
1585457981
Sun Mar 29 12:59:41 2020

1s
*/

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static std::chrono::time_point<std::chrono::steady_clock> now() noexcept; 
// (C++11 起)

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#include <windows.h>

#include <chrono>
#include <iostream>
using namespace std;
int main() {
  chrono::steady_clock::time_point start = chrono::steady_clock::now();

  Sleep(1000);  // do some stuff...

  chrono::steady_clock::time_point end = chrono::steady_clock::now();

  chrono::duration<double> ans = end - start;

  cout << ans.count() << 's' << endl;
  return 0;
}

/* 输出：
1.01495s
*/

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DWORD GetTickCount();

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#include <windows.h>
#include <iostream>
using namespace std;
int main() {
  DWORD start = GetTickCount();

  Sleep(1000);  // do some stuff...

  DWORD end = GetTickCount();

  cout << end - start << "ms" << endl;
  return 0;
}

/*输出：
1016ms
*/

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ULONGLONG GetTickCount64();

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#include <windows.h>
#include <iomanip>
#include <iostream>
using namespace std;
int main() {
  ULONGLONG start = GetTickCount64();

  Sleep(1000); // do some stuff...

  ULONGLONG end = GetTickCount64();

  cout << end - start << "ms" << endl;
  return 0;
}

/* 输出：
1015ms
*/

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#include <windows.h>
#include <iostream>
using namespace std;
int main() {
  LARGE_INTEGER freq;
  QueryPerformanceFrequency(&freq);  // 获取性能计数器的频率

  LARGE_INTEGER start;
  QueryPerformanceCounter(&start);

  Sleep(1000); // do some stuff...

  LARGE_INTEGER end;
  QueryPerformanceCounter(&end);

  double misTime =
      (end.QuadPart - start.QuadPart) / (freq.QuadPart / 1000000.0);  // 微秒
  double milTime =
      (end.QuadPart - start.QuadPart) / (freq.QuadPart / 1000.0);  // 毫秒
  double sTime = (end.QuadPart - start.QuadPart) / freq.QuadPart;  // 秒

  cout << misTime << " microseconds" << endl;
  cout << milTime << " milliseconds" << endl;
  cout << sTime << " seconds" << endl;

  return 0;
}

/* 输出：
1.00367e+06 microseconds
1003.67 milliseconds
1 seconds
*/