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  4. How to restrict QLineEdit to take "comma" and "plus" as input value?
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How to restrict QLineEdit to take "comma" and "plus" as input value?

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  • K Offline
    K Offline
    kishore_hemmady
    wrote on last edited by kishore_hemmady
    #3

    thank you @LeLev

    please tell me how can i set range for this field using the below snippet?

    QRegExp rx("-?\\d{1,3}");
    QValidator *validator = new QRegExpValidator(rx, this);
    ui->VideoHeight->setValidator(validator);
    

    I want to set the range between 1 to 100.

    Gojir4G 1 Reply Last reply
    0
    • K kishore_hemmady

      thank you @LeLev

      please tell me how can i set range for this field using the below snippet?

      QRegExp rx("-?\\d{1,3}");
      QValidator *validator = new QRegExpValidator(rx, this);
      ui->VideoHeight->setValidator(validator);
      

      I want to set the range between 1 to 100.

      Gojir4G Offline
      Gojir4G Offline
      Gojir4
      wrote on last edited by
      #4

      @kishore_hemmady Hi,

      Better to use QIntValidator in this case:

      QValidator *validator = new QIntValidator(1, 100, this);
      // the edit lineedit will only accept integers between 1 and 100 
      edit->setValidator(validator);
      
      1 Reply Last reply
      4
      • K Offline
        K Offline
        kishore_hemmady
        wrote on last edited by
        #5

        hi @Gojir4 ,

        thank you,
        i had used the same but ,i was able to enter comma (,)and plus (+) symbol if i use the above code,which i don't want.

        1 Reply Last reply
        0
        • M Offline
          M Offline
          mad-hatter
          wrote on last edited by mad-hatter
          #6

          Hello,

          You could install an eventFilter on your lineEdit and trap the comma, '+' and '-' sign and use the int validator as well.

          Regards

          1 Reply Last reply
          0
          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by
            #7

            Hi,

            What is your widget purpose ?

            Interested in AI ? www.idiap.ch
            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

            1 Reply Last reply
            0
            • KillerSmathK Offline
              KillerSmathK Offline
              KillerSmath
              wrote on last edited by KillerSmath
              #8

              @kishore_hemmady

              You can create a RegularExpression to accept just 0 or 1-99 or 100

              QRegExp regExp = QRegExp("^(0|[1-9][0-9]?|100)$");
              

              | = OR
              ? = OPTIONAL

              NOTE: if you are using Qt5.*, i suggest you to use QRegularExpression instead of QRegExp, because QRegExp is an old class of regular expression of Qt4 :)
              http://doc.qt.io/qt-5/qregularexpression.html#notes-for-qregexp-users

              @Computer Science Student - Brazil
              Web Developer and Researcher
              “Sometimes it’s the people no one imagines anything of who do the things that no one can imagine.” - Alan Turing

              1 Reply Last reply
              6
              • K Offline
                K Offline
                kishore_hemmady
                wrote on last edited by kishore_hemmady
                #9

                Hi @SGaist

                its a variable , i have to set it like this,
                ui->height->setValidator(newQIntValidator(minValue,maxValue, this));
                if i use this then the height field will take + and , values.

                minValue and maxValue values are system dependent

                1 Reply Last reply
                0
                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #10

                  If you still have a comma that you can enter then there's something else that's wrong neither QIntValidator nor QSpinBox allows that kind of number.

                  What is the problem with the plus sign ?

                  Interested in AI ? www.idiap.ch
                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                  1 Reply Last reply
                  2
                  • KillerSmathK Offline
                    KillerSmathK Offline
                    KillerSmath
                    wrote on last edited by KillerSmath
                    #11

                    @kishore_hemmady
                    If you really need to avoid the + signal and just accept numbers.

                    1) You can create a custom QIntValidator and reimplement the validate function to accept what you need.

                    // customintvalidator.h
                    #include <QIntValidator>
                    
                    class CustomIntValidator : public QIntValidator {
                    public:
                        CustomIntValidator (int bottom, int top, QObject * parent) : QIntValidator(bottom, top, parent) {}
                    
                        QValidator::State validate(QString &s, int &pos) const {
                            Q_UNUSED(pos);
                            if (s.isEmpty()){
                                return QValidator::Intermediate; // accept but is not valid
                            }
                    
                            if( s.startsWith("+") ){
                                return QValidator::Invalid;
                            }
                    
                            if( bottom() < 0 && s.startsWith("-") && s.length() == 1 ){
                                return QValidator::Intermediate;
                            }
                    
                            // check number
                    
                            bool isNumber;
                            int value = locale().toInt(s, &isNumber);
                    
                            if (isNumber && bottom() <= value && value <= top()) {
                                return QValidator::Acceptable;
                            }
                    
                            return QValidator::Invalid;
                        }
                    
                    };
                    
                    // mainwindow.cpp
                    ui->lineEdit->setValidator(new CustomIntValidator(-100 , 100, this));
                    

                    This custom IntValidator accepts positive and negative numbers incluinding -0 interpreted as 0
                    And ignore comma, dot and plus simbols.

                    2) You can create a filter to capture the Comma and Plus Keydown event

                    // filterobject.h
                    #include <QEvent>
                    #include <QKeyEvent>
                    #include <QObject>
                    
                    class FilterObject : public QObject {
                    public:
                        explicit FilterObject(QObject *parent = 0) : QObject(parent){
                        }
                        
                        bool eventFilter(QObject *object, QEvent *event)
                        {
                            Q_UNUSED(object);
                            if (event->type() == QEvent::KeyPress) {
                                QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
                                switch(keyEvent->key()){
                                case Qt::Key_Plus:
                                    return true;
                                case Qt::Key_Comma:
                                    return true;
                                default:
                                    return false;
                                }
                            }
                            return false;
                        }
                    };
                    
                    // mainwindow.cpp
                    ui->lineEdit->installEventFilter(new FilterObject(ui->lineEdit));
                    

                    I don't believe these are the best solutions for this problem but works.

                    @Computer Science Student - Brazil
                    Web Developer and Researcher
                    “Sometimes it’s the people no one imagines anything of who do the things that no one can imagine.” - Alan Turing

                    K 1 Reply Last reply
                    4
                    • KillerSmathK KillerSmath

                      @kishore_hemmady
                      If you really need to avoid the + signal and just accept numbers.

                      1) You can create a custom QIntValidator and reimplement the validate function to accept what you need.

                      // customintvalidator.h
                      #include <QIntValidator>
                      
                      class CustomIntValidator : public QIntValidator {
                      public:
                          CustomIntValidator (int bottom, int top, QObject * parent) : QIntValidator(bottom, top, parent) {}
                      
                          QValidator::State validate(QString &s, int &pos) const {
                              Q_UNUSED(pos);
                              if (s.isEmpty()){
                                  return QValidator::Intermediate; // accept but is not valid
                              }
                      
                              if( s.startsWith("+") ){
                                  return QValidator::Invalid;
                              }
                      
                              if( bottom() < 0 && s.startsWith("-") && s.length() == 1 ){
                                  return QValidator::Intermediate;
                              }
                      
                              // check number
                      
                              bool isNumber;
                              int value = locale().toInt(s, &isNumber);
                      
                              if (isNumber && bottom() <= value && value <= top()) {
                                  return QValidator::Acceptable;
                              }
                      
                              return QValidator::Invalid;
                          }
                      
                      };
                      
                      // mainwindow.cpp
                      ui->lineEdit->setValidator(new CustomIntValidator(-100 , 100, this));
                      

                      This custom IntValidator accepts positive and negative numbers incluinding -0 interpreted as 0
                      And ignore comma, dot and plus simbols.

                      2) You can create a filter to capture the Comma and Plus Keydown event

                      // filterobject.h
                      #include <QEvent>
                      #include <QKeyEvent>
                      #include <QObject>
                      
                      class FilterObject : public QObject {
                      public:
                          explicit FilterObject(QObject *parent = 0) : QObject(parent){
                          }
                          
                          bool eventFilter(QObject *object, QEvent *event)
                          {
                              Q_UNUSED(object);
                              if (event->type() == QEvent::KeyPress) {
                                  QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
                                  switch(keyEvent->key()){
                                  case Qt::Key_Plus:
                                      return true;
                                  case Qt::Key_Comma:
                                      return true;
                                  default:
                                      return false;
                                  }
                              }
                              return false;
                          }
                      };
                      
                      // mainwindow.cpp
                      ui->lineEdit->installEventFilter(new FilterObject(ui->lineEdit));
                      

                      I don't believe these are the best solutions for this problem but works.

                      K Offline
                      K Offline
                      kishore_hemmady
                      wrote on last edited by
                      #12

                      hi @KillerSmath
                      thank you for your answer.

                      1 Reply Last reply
                      1

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