How would one set an input validator on a QLineEdit such that it restricts it to a valid IP address? i.e. x.x.x.x where x must be between 0 and 255.and x can not be empty
2 Answers
You are looking for QRegExp and QValidator, to validate an IPv4 use this expresion:
\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b
Example:
QRegExp ipREX("\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b");
ipREX.setCaseSensitivity(Qt::CaseInsensitive);
ipREX.setPatternSyntax(QRegExp::RegExp);
Now, use it as validator of your text lineedit:
QRegExpValidator regValidator( rx, 0 );
ui->lineEdit->setValidator( ®Validator );
Now, just read your input and the validator will validate it =). If you want to do it manually, try something like this:
ui->lineEdit->setText( "000.000.000.000" );
const QString input = ui->lineEdit->text();
// To check if the text is valid:
qDebug() << "IP validation: " << myREX.exactMatch(input);
There is another way to made it using Qt classes, QHostAddress and QAbstractSocket:
QHostAddress address(input);
if (QAbstractSocket::IPv4Protocol == address.protocol())
{
qDebug("Valid IPv4 address.");
}
else if (QAbstractSocket::IPv6Protocol == address.protocol())
{
qDebug("Valid IPv6 address.");
}
else
{
qDebug("Unknown or invalid address.");
}
2 Comments
Rishabh Bansal
It is taking the value greater than 255 also. and we can enter 133.133. instead of 4 parts. it is able to take less than 4 parts of ip address. Please suggest how we can validate that ip address must contain 4 parts with range 0-255
mohabouje
See my last changes. Here's the best one I've found so far: \b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b
The answer is here
In short: You have to set QRegExpValidator with the appropriate Regular Expression for IP4 adresses.
QValidator? Start from there. You have basically two options, create your own subclass "IpValidator", or use the regular expression validators.