QIntValidators dont work for me

[JonB]

@nullbuil7
Here is the example from the docs:

QValidator *validator = new QIntValidator(100, 999, this);
QLineEdit *edit = new QLineEdit(this);

// the edit lineedit will only accept integers between 100 and 999
edit->setValidator(validator);

Are you saying this does not work as documented?

[nullbuil7]

yes it doesn't work. if you say i want top to be 4000 it can go up to 9999. i don't know why

[SGaist]

Hi,

The fact that you can enter higher value does not make sais value valid.

By the way, which version of Qt are you using ?

[JonB]

@nullbuil7
In the case of the docs example or your own code, what does edit->validate() return? Intermediate? Are you in the situation described in another example for QIntValidator v(100, 900, this); where it says:

Notice that the value 999 returns Intermediate. Values consisting of a number of digits equal to or less than the max value are considered intermediate. This is intended because the digit that prevents a number from being in range is not necessarily the last digit typed.

because this ties with your maximum of 255 and your "other than it should be three numbers [digits]"? When you know the user has finished typing you need the validator to return Acceptable, not Intermediate (or Invalid), for the input to be valid. A validator is not just about preventing the user from typing characters, it's also about checking the validity of the characters it has allowed the user to type, so two aspects.

[nullbuil7]

i searched the web and made my own validator but i don't know how to use it. what should i do?

#ifndef VALIDATOR_H
#define VALIDATOR_H
#include <QObject>
#include <QValidator>

class binValidator : public QValidator
{
    Q_OBJECT
public:
    explicit binValidator(QObject *parent = nullptr);
    virtual State validate(QString & input, int & pos) const override
    {
        if (input.isEmpty())
            return Acceptable;

        bool b;
        int val = input.toInt(&b);

        if ((b == true) && (val >= 0) && (val <= 255))
        {
            return Acceptable;
        }
        return Invalid;
    }
};

#endif

[Xiao Yang]

@nullbuil7 yes, i found it(QIntValidator, QDoubleValidtor) doesn't work too. my QLineEdit top can be input "999" when i set QIntValidator(0, 500)

[VRonin]

Indeed it has been explicitly coded to return intermidiate in that case.

You can use this:

class HarshIntValidator : public QIntValidator{
    Q_OBJECT
    Q_DISABLE_COPY(HarshIntValidator)
public:
    using QIntValidator::QIntValidator;
    State validate(QString & input, int & pos) const override{
        const State originalRes = QIntValidator::validate(input,pos);
        if(originalRes==Intermediate){
            const auto extracted = locale().toLongLong(input);
            if(extracted>0){
                if(extracted>top() && -extracted<bottom())
                    return Invalid;
            }
            else if(extracted<bottom())
                return Invalid;
        }
        return  originalRes;
    }
};

you can use it exactly as you use QIntValidator:

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QLineEdit w;
    HarshIntValidator valid(0,255);
    w.setValidator(&valid);
    w.show();
    return a.exec();
}

[Christian Ehrlicher]

See also https://bugreports.qt.io/browse/QTBUG-76649 and other related bug reports why it's the way it is.

[DrewB]

To limit 0 to 255 you can use QRegularExpressionValidator instead of QIntValidator

QRegularExpressionValidator* decValidator = new QRegularExpressionValidator(QRegularExpression("([01][0-9][0-9]|2[0-4][0-9]|25[0-5])"), decEdit);
decEdit->setValidator(decValidator);

[JonB]

@DrewB Does this behave any differently from the clearer QIntValidator?