Solution to the problem that qlineedit setting qdoublevalidator setting range is invalid

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problem

When developing , about QLineEdit Set its value to be limited and input range limited .

QLineEdit Set up QDoubleValidator Invalid , Set up QIntValidator It works .

Invalid code and valid code

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        #if 0
        
//  Floating point invalid code 
        
    ui->lineEdit_t->setValidator(new DoubleValidator(40, 80, 1);
        
#else
        
//  Floating point number valid code 
        
    QDoubleValidator * doubleValidator = new QDoubleValidator(40, 80, 1);
        
    doubleValidator->setNotation(QDoubleValidator::StandardNotation);
        
    ui->lineEdit_t->setValidator(doubleValidator);
        
#end
        
//  Integer valid code 
        
    ui->lineEdit_coverT->setValidator(new QIntValidator(0, 110));
       
       

        
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Add （2021 year 05 month 17 Japan ）

The above methods , Indeed, only the entered digits can be displayed , Because I am a floating-point number within a limited range of integers , So ignore , To limit floating-point numbers with decimals , Overload it .

Particular attention ： For example, restrictions 1.0-10, that QLineEdit After use, you can enter “10.”, As a string to double by 10, But pay attention when saving as a string . The problem of

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        #ifndef MYDOUBLEVALIDATOR_H
        
#define MYDOUBLEVALIDATOR_H
        
#include <QDoubleValidator>
        

        
class MyDoubleValidator: public QDoubleValidator
        
{
        
public:
        
    MyDoubleValidator(double bottom, double top, int decimals, QObject * parent = 0) :
        
        QDoubleValidator(bottom, top, decimals, parent)
        
    {
        
    }
        

        
    QValidator::State validate(QString &s, int &i) const
        
    {
        
        if (s.isEmpty() || s == "-") {
        
            return QValidator::Intermediate;
        
        }
        

        
        QChar decimalPoint = locale().decimalPoint();
        

        
        if(s.indexOf(decimalPoint) != -1) {
        
            int charsAfterPoint = s.length() - s.indexOf(decimalPoint) - 1;
        

        
            if (charsAfterPoint > decimals()) {
        
                return QValidator::Invalid;
        
            }
        
        }
        

        
        bool ok;
        
        double d = locale().toDouble(s, &ok);
        

        
        if (ok && d >= bottom() && d <= top()) {
        
            return QValidator::Acceptable;
        
        } else {
        
            return QValidator::Invalid;
        
        }
        
    }
        
};
        

        
#endif // MYDOUBLEVALIDATOR_H
       
       

        
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