How can I find out in Win64 how many processor cores there are in the system?

Mar 11 2012

Author: Andrey Karpov

To get information about the number of processor cores in the system, you may use the Windows environment variable NUMBER_OF_PROCESSORS. Below is a fragment of C++ code where the WinAPI GetEnvironmentVariable method is used to extract and display the contents of this environment variable.

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

#define VARNAME TEXT("NUMBER_OF_PROCESSORS")
#define BUFSIZE 4096

int main()
{
  TCHAR buf[BUFSIZE];
  DWORD dwRet = GetEnvironmentVariable(VARNAME, buf, BUFSIZE);
  if (dwRet > 0 && dwRet < BUFSIZE)
    _tprintf(_T("Number of processors: %s\n"), buf);

  return 0;
}