#include <Windows.h>
//原理：调用GetProcessTimes()，并与上次调用得到的结果相减，即得到某段时间内CPU的使用时间
//C++ 获取特定进程规定CPU使用率  原文：http://blog.csdn.net/liuqx97bb/article/details/52058657
class CPUusage {
private:  typedef long long          int64_t;  typedef unsigned long long uint64_t;  HANDLE _hProcess;    int _processor;    //cpu数量    int64_t _last_time;         //上一次的时间
    int64_t _last_system_time;    // 时间转换    uint64_t file_time_2_utc(const FILETIME* ftime);  // 获得CPU的核数    int get_processor_number();  //初始化  void init()  {  _last_system_time = 0;  _last_time = 0;  _hProcess = 0;  }  //关闭进程句柄  void clear()  {  if (_hProcess) {  CloseHandle(_hProcess);  _hProcess = 0;  }  }  public:  CPUusage(DWORD ProcessID) {   init();   _processor = get_processor_number();  setpid(ProcessID);  }  CPUusage() { init(); _processor = get_processor_number(); }  ~CPUusage() { clear(); }  //返回值为进程句柄，可判断OpenProcess是否成功
    HANDLE setpid(DWORD ProcessID) {   clear();    //如果之前监视过另一个进程，就先关闭它的句柄
        init();   return _hProcess= OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, false, ProcessID);   }  //-1 即为失败或进程已退出； 如果成功，首次调用会返回-2（中途用setpid更改了PID后首次调用也会返回-2）  float get_cpu_usage();
};  

float CPUusage::get_cpu_usage()
{  FILETIME now;  FILETIME creation_time;  FILETIME exit_time;  FILETIME kernel_time;  FILETIME user_time;  int64_t system_time;  int64_t time;  int64_t system_time_delta;  int64_t time_delta;  DWORD exitcode;  float cpu = -1;  if (!_hProcess) return -1;  GetSystemTimeAsFileTime(&now);  //判断进程是否已经退出  GetExitCodeProcess(_hProcess, &exitcode);    if (exitcode != STILL_ACTIVE) {  clear();  return -1;  }  //计算占用CPU的百分比  if (!GetProcessTimes(_hProcess, &creation_time, &exit_time, &kernel_time, &user_time))  {  clear();  return -1;  }  system_time = (file_time_2_utc(&kernel_time) + file_time_2_utc(&user_time))  / _processor;  time = file_time_2_utc(&now);  //判断是否为首次计算  if ((_last_system_time == 0) || (_last_time == 0))  {  _last_system_time = system_time;  _last_time = time;  return -2;  }  system_time_delta = system_time - _last_system_time;  time_delta = time - _last_time;  if (time_delta == 0) {  return -1;  }  cpu = (float)system_time_delta * 100 / (float)time_delta;  _last_system_time = system_time;  _last_time = time;  return cpu;
}  CPUusage::uint64_t CPUusage::file_time_2_utc(const FILETIME* ftime)
{  LARGE_INTEGER li;  li.LowPart = ftime->dwLowDateTime;  li.HighPart = ftime->dwHighDateTime;  return li.QuadPart;
}  int CPUusage::get_processor_number()
{  SYSTEM_INFO info;  GetSystemInfo(&info);  return info.dwNumberOfProcessors;
}  

#include "CPUusage.h"
int _tmain(int argc, _TCHAR* argv[])
{  CPUusage usg(12316);  for (int i = 0; i < 10; i++)  {  float cpu = usg.get_cpu_usage();  printf("Taskmgr.exe: %.2f%%\n", cpu);  Sleep(500);  }  usg.setpid(11084);  for (int i = 0; i < 10; i++)  {  float cpu = usg.get_cpu_usage();  printf("devenv.exe: %.2f%%\n", cpu);  Sleep(1000);  }  return 0;
}