#include <windows.h>
#include <stdio.h>
#define THREADCOUNT 4
DWORD dwTlsIndex;
VOID ErrorExit(LPSTR); 
VOID CommonFunc(VOID)
{
   LPVOID lpvData; 
// Retrieve a data pointer for the current thread. 
   lpvData = TlsGetValue(dwTlsIndex);
   if ((lpvData == 0) && (GetLastError() != ERROR_SUCCESS))
      ErrorExit("TlsGetValue error"); 
// Use the data stored for the current thread. 
   printf("common: thread %d: lpvData=%lx\n",
      GetCurrentThreadId(), lpvData); 
   Sleep(5000);
} 
DWORD WINAPI ThreadFunc(VOID)
{
   LPVOID lpvData; 
// Initialize the TLS index for this thread. 
   lpvData = (LPVOID) LocalAlloc(LPTR, 256);
   if (! TlsSetValue(dwTlsIndex, lpvData))
      ErrorExit("TlsSetValue error"); 
   printf("thread %d: lpvData=%lx\n", GetCurrentThreadId(), lpvData); 
   CommonFunc(); 
// Release the dynamic memory before the thread returns. 
   lpvData = TlsGetValue(dwTlsIndex);
   if (lpvData != 0)
      LocalFree((HLOCAL) lpvData); 
   return 0;
} 
int main(VOID)
{
   DWORD IDThread;
   HANDLE hThread[THREADCOUNT];
   int i; 
// Allocate a TLS index. 
   if ((dwTlsIndex = TlsAlloc()) == TLS_OUT_OF_INDEXES)
      ErrorExit("TlsAlloc failed"); 
// Create multiple threads. 
   for (i = 0; i < THREADCOUNT; i++)
   {
      hThread[i] = CreateThread(NULL, // default security attributes
         0,                           // use default stack size
         (LPTHREAD_START_ROUTINE) ThreadFunc, // thread function
         NULL,                    // no thread function argument
         0,                       // use default creation flags
         &IDThread);              // returns thread identifier 
   // Check the return value for success.
      if (hThread[i] == NULL)
         ErrorExit("CreateThread error\n");
   } 
   for (i = 0; i < THREADCOUNT; i++)
      WaitForSingleObject(hThread[i], INFINITE); 
   TlsFree(dwTlsIndex); 
   return 0;
}
VOID ErrorExit (LPSTR lpszMessage)
{
   fprintf(stderr, "%s\n", lpszMessage);
   ExitProcess(0);
}