MFC ListControl选取多行数据并读取

void CGlassDetectDlg::OnBnClickedButton14()
{
    // TODO: Add your control notification handler code here

    

    CString str;
    POSITION pos=m_List.GetFirstSelectedItemPosition(); //pos选中的首行位置
    if(pos==NULL)
        AfxMessageBox("no item were selected!");
    else
    {
        while(pos)   //如果你选择多行
        {
            int nIdx=-1;
            nIdx= m_List.GetNextSelectedItem(pos);
            
            if(nIdx >=0&&nIdx<m_List.GetItemCount())
            {
                str =m_List.GetItemText(nIdx,4);//获取指定列，为字符串形式
            }   
        }
    }
}