Реализация поиска запущенных копий приложения

#include <windows.h>
 
static char appname[] = "myEnumWin";
 
long CALLBACK winProc(HWND, UINT, WPARAM, LPARAM);
 
BOOL CALLBACK enumProc(HWND hwnd, LPARAM counter)
{
   char className[128];
 
   if (GetClassName(hwnd, &(className[0]), sizeof(className)))
   {
      if (!strcmp(className, appname))
      {
         (*(int *)counter) += 1;
      }
   }
 
   return 1;
}
 
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
   int windowCounter = 0;
   EnumWindows(enumProc, (LPARAM)&windowCounter);
   if (windowCounter > 1) MessageBox(NULL, NULL, NULL, MB_OK);
 
   WNDCLASSEX wclass;
   HWND wh;
   MSG msg;
 
 
   wclass.cbSize = sizeof(wclass);
   wclass.style = CS_HREDRAW | CS_VREDRAW;
   wclass.lpfnWndProc = winProc;
   wclass.hInstance = GetModuleHandle(NULL);
   wclass.hIcon = NULL;
   wclass.hCursor = LoadCursor(NULL, IDC_ARROW);
   wclass.hbrBackground = (HBRUSH) GetStockObject(COLOR_WINDOWFRAME);
   wclass.lpszMenuName = NULL;
   wclass.lpszClassName = appname;
   wclass.hIconSm = NULL;
 
   wclass.cbClsExtra = 0;
   wclass.cbWndExtra = 0;
 
   RegisterClassEx(&wclass);
 
   wh = CreateWindow(appname,
      "demowin",
      WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT,
      CW_USEDEFAULT,
      240,
      320,
      NULL,
      NULL,
      GetModuleHandle(NULL),
      NULL
   );
 
   ShowWindow(wh, SW_SHOW);
   while (GetMessage(&msg, NULL, 0, 0)) {
      TranslateMessage(&msg);
      DispatchMessage(&msg);
   }
   
 
   ExitProcess(0);
}
 
long CALLBACK winProc(HWND wh, UINT msg, WPARAM wparam, LPARAM lparam) {
   switch (msg)
   {
      case WM_KEYDOWN:
         if (wparam == VK_ESCAPE) DestroyWindow(wh);
         break;
 
      case WM_DESTROY:
         PostQuitMessage(0);
         break;
 
      default:   
         return DefWindowProc(wh, msg, wparam, lparam);
   }
   return 0;
}