学步园

HWND hWnd = ::FindWindow(L"SciCalc", L"Calculator");

if (NULL != hWnd)
{
   ::MessageBox(hWnd, L"", L"OK", 0);

   HWND hEdit = ::GetDlgItem(hWnd, 403);

   ::SendMessage(hEdit, WM_SETTEXT, 0, (LPARAM)L"123");
}