GetActiveProcessorCount function (winbase.h)

Returns the number of active processors in a processor group or in the system.


DWORD GetActiveProcessorCount(
  [in] WORD GroupNumber


[in] GroupNumber

The processor group number. If this parameter is ALL_PROCESSOR_GROUPS, the function returns the number of active processors in the system.

Return value

If the function succeeds, the return value is the number of active processors in the specified group.

If the function fails, the return value is zero. To get extended error information, use GetLastError.


To compile an application that uses this function, set _WIN32_WINNT >= 0x0601. For more information, see Using the Windows Headers.


Requirement Value
Minimum supported client Windows 7 [desktop apps only]
Minimum supported server Windows Server 2008 R2 [desktop apps only]
Target Platform Windows
Header winbase.h (include Windows.h)
Library Kernel32.lib
DLL Kernel32.dll