检查IP地址输入是否正确

bool MainWindow::IsIPaddress(QString ip)

{
    QRegExp rx2("(\\d+)(\\.)(\\d+)(\\.)(\\d+)(\\.)(\\d+)");
    int pos = rx2.indexIn(ip);

    if(pos>-1)
    {
         for(int i=0;i<4;i++)
        {
            if( rx2.cap(i*2+1).toInt()>=255 )
            {
                QMessageBox::information(this, tr("错误"), tr("IP地址错误"));
                return false;
            }
        }

        if(rx2.cap(7).toInt()==0)
        {
            QMessageBox::information(this, tr("错误"), tr("IP地址错误"));
            return false;
        }

        if(rx2.cap(7).toInt()==0)
        {
            QMessageBox::information(this, tr("错误"), tr("IP地址错误"));
            return false;
        }
    }
    else
    {
        QMessageBox::information(this, tr("错误"), tr("IP地址错误"));
        return false;
    }

    return true;
}