 HKEY hk;
 
  int result = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
               _T("SYSTEM\\ControlSet001\\Control\\Session Manager\\Environment"),
               NULL,
               KEY_READ, &hk );
 
  if(result != ERROR_SUCCESS)
  {
    if(result == ERROR_FILE_NOT_FOUND)
    {
 
      MessageBox(g.hwnd,_T("no such key in RegOpenKeyEx"),_T("title"),MB_ICONWARNING);
    }
 
    else
   
    return;
  }
 
  DWORD lsize;
 
  result = RegQueryValueEx(hk, _T("Path"),NULL,NULL,
              NULL, &lsize);
 
 
  if(result != ERROR_SUCCESS)
  {
    if(result == ERROR_FILE_NOT_FOUND)
    {
 
      MessageBox(g.hwnd,_T("no such key in RegQueryValue"),_T("title"),MB_ICONWARNING);
    }
    else if(result == ERROR_MORE_DATA)
    {
      MessageBox(g.hwnd,_T("need more buffer"),_T("title"),MB_ICONWARNING);
    }
    else
   
    return;
  }
  TCHAR *value = (TCHAR * )malloc(lsize * sizeof(TCHAR));
  result = RegQueryValueEx(hk, _T("Path"),NULL,NULL,
              (LPBYTE)value, &lsize);
  if(result != ERROR_SUCCESS)
  {
    if(result == ERROR_FILE_NOT_FOUND)
    {
 
      MessageBox(g.hwnd,_T("no such key in RegQueryValue"),_T("title"),MB_ICONWARNING);
    }
    else if(result == ERROR_MORE_DATA)
    {
      MessageBox(g.hwnd,_T("need more buffer"),_T("title"),MB_ICONWARNING);
    }
    else
    
    return;
  }
  SetWindowText(g.hwndEdit,value);
  free(value);
  RegCloseKey(hk);

新手常見問題
RegSetValueEx運行時失敗，返回代碼為5，
解決方法：這種情況是由于對注冊表訪問權限不夠，拒絕訪問的意思，因此，注意看看權限是否不夠，如果改為
KEY_ALL_ACCESS就沒問題了，這樣讀寫等權限都可以。