找出系统中处理器的数目并检查其状态

#include <windows.h>
#include <stdio.h>
#include <conio.h>
int main(int argc, char* argv[])
{
//初始化SYSTEM_INFO数据结构
SYSTEM_INFO si;
GetSystemInfo(&si);
printf("当前有%d个处理器。/n",si.dwNumberOfProcessors);
//检查每个处理器的活动状态
for(DWORD dwPro=0;dwPro<si.dwNumberOfProcessors;dwPro++)
{
printf(" 处理器%d",dwPro);
if((si.dwActiveProcessorMask&(1<<dwPro))!=0)
{
printf("处于活动状态。/n");
}
else
{
printf("处于休眠状态。/n");
}
}
getch();
return 0;
}

检测CPU的使用率（以下转自 C++Builder 研究 - http://www.ccrun.com/article.asp?i=424&d=7jw23a）

#include <windows.h>
#include <conio.h>
#include <stdio.h>

#define SystemBasicInformation 0
#define SystemPerformanceInformation 2
#define SystemTimeInformation 3

#define Li2Double(x) ((double)((x).HighPart) * 4.294967296E9 + (double)((x).LowPart))

typedef struct
{
DWORD dwUnknown1;
ULONG uKeMaximumIncrement;
ULONG uPageSize;
ULONG uMmNumberOfPhysicalPages;
ULONG uMmLowestPhysicalPage;
ULONG uMmHighestPhysicalPage;
ULONG uAllocationGranularity;
PVOID pLowestUserAddress;
PVOID pMmHighestUserAddress;
ULONG uKeActiveProcessors;
BYTE bKeNumberProcessors;
BYTE bUnknown2;
WORD wUnknown3;
} SYSTEM_BASIC_INFORMATION;

typedef struct
{
LARGE_INTEGER liIdleTime;
DWORD dwSpare[76];
} SYSTEM_PERFORMANCE_INFORMATION;

typedef struct
{
LARGE_INTEGER liKeBootTime;
LARGE_INTEGER liKeSystemTime;
LARGE_INTEGER liExpTimeZoneBias;
ULONG uCurrentTimeZoneId;
DWORD dwReserved;
} SYSTEM_TIME_INFORMATION;

// ntdll!NtQuerySystemInformation (NT specific!)
//
// The function copies the system information of the
// specified type into a buffer
//
// NTSYSAPI
// NTSTATUS
// NTAPI
// NtQuerySystemInformation(
// IN UINT SystemInformationClass, // information type
// OUT PVOID SystemInformation, // pointer to buffer
// IN ULONG SystemInformationLength, // buffer size in bytes
// OUT PULONG ReturnLength OPTIONAL // pointer to a 32-bit
// // variable that receives
// // the number of bytes
// // written to the buffer
// );
typedef LONG (WINAPI *PROCNTQSI)(UINT,PVOID,ULONG,PULONG);

PROCNTQSI NtQuerySystemInformation;

void main(void)
{
SYSTEM_PERFORMANCE_INFORMATION SysPerfInfo;
SYSTEM_TIME_INFORMATION SysTimeInfo;
SYSTEM_BASIC_INFORMATION SysBaseInfo;
double dbIdleTime;
double dbSystemTime;
LONG status;
LARGE_INTEGER liOldIdleTime = {0,0};
LARGE_INTEGER liOldSystemTime = {0,0};
NtQuerySystemInformation = (PROCNTQSI)GetProcAddress(
GetModuleHandle("ntdll"),
"NtQuerySystemInformation"
);

if (!NtQuerySystemInformation)
return;

// get number of processors in the system
status = NtQuerySystemInformation(SystemBasicInformation,&SysBaseInfo,sizeof(SysBaseInfo),NULL);
if (status != NO_ERROR)
return;

printf("/nCPU Usage (press any key to exit): ");
while(!_kbhit())
{
// get new system time
status = NtQuerySystemInformation(SystemTimeInformation,&SysTimeInfo,sizeof(SysTimeInfo),0);
if (status!=NO_ERROR)
return;

// get new CPU's idle time
status = NtQuerySystemInformation(SystemPerformanceInformation,&SysPerfInfo,sizeof(SysPerfInfo),NULL);
if (status != NO_ERROR)
return;

// if it's a first call - skip it
if (liOldIdleTime.QuadPart != 0)
{
// CurrentValue = NewValue - OldValue
dbIdleTime = Li2Double(SysPerfInfo.liIdleTime) - Li2Double(liOldIdleTime);
dbSystemTime = Li2Double(SysTimeInfo.liKeSystemTime) - Li2Double(liOldSystemTime);

// CurrentCpuIdle = IdleTime / SystemTime
dbIdleTime = dbIdleTime / dbSystemTime;

// CurrentCpuUsage% = 100 - (CurrentCpuIdle * 100) / NumberOfProcessors
dbIdleTime = 100.0 - dbIdleTime * 100.0 / (double)SysBaseInfo.bKeNumberProcessors + 0.5;

printf("/b/b/b/b%3d%%",(UINT)dbIdleTime);
}

// store new CPU's idle and system time
liOldIdleTime = SysPerfInfo.liIdleTime;
liOldSystemTime = SysTimeInfo.liKeSystemTime;

// wait one second
Sleep(1000);
}
printf("/n");
}