QLineEdit problem

**kumarpraveen** · 12th July 2010, 05:37

hi,
I am writing a simple converter application here when we give a decimal number (0-255) then its convert in hex and binary or hex is convert decimal and binary ..., all are synchronize using signal-slot. i use validator for control use input. but it not showing me desired result.

Thanks in advance

ByteConvertorDialog.h

Qt Code:

Switch view

#ifndef BYTECONVERTERDIALOG_H
#define BYTECONVERTERDIALOG_H
 
#include <QWidget>
 
class QLineEdit; //forward declartion
 
class ByteConverterDialog : public QWidget
{
    Q_OBJECT
public:
    ByteConverterDialog();
private:
    QLineEdit* decEdit;
    QLineEdit* hexEdit;
    QLineEdit* binEdit;
private slots:
    void decChanged(const QString&);
    void hexChanged(const QString&);
    void binChanged(const QString&);
};
 
#endif // BYTECONVERTERDIALOG_H

#ifndef BYTECONVERTERDIALOG_H
#define BYTECONVERTERDIALOG_H

#include <QWidget>

class QLineEdit; //forward declartion

class ByteConverterDialog : public QWidget
{
    Q_OBJECT
public:
    ByteConverterDialog();
private:
    QLineEdit* decEdit;
    QLineEdit* hexEdit;
    QLineEdit* binEdit;
private slots:
    void decChanged(const QString&);
    void hexChanged(const QString&);
    void binChanged(const QString&);
};

#endif // BYTECONVERTERDIALOG_H

To copy to clipboard, switch view to plain text mode

ByteConvertorDialog.cpp

Qt Code:

Switch view

#include <QLineEdit>
#include <QLabel>
#include <QPushButton>
#include <QVBoxLayout>
#include <QHBoxLayout>
#include <QGridLayout>
#include <QIntValidator>
#include <QRegExpValidator>
#include "ByteConverterDialog.h"
 
ByteConverterDialog::ByteConverterDialog()
{
    QVBoxLayout *mainLayout = new QVBoxLayout(this);
    QGridLayout *editLayout = new QGridLayout;
    QHBoxLayout *buttonLayout = new QHBoxLayout;
 
    mainLayout->addLayout(editLayout);
    mainLayout->addStretch();
    mainLayout->addLayout(buttonLayout);
 
    QLabel *decLabel = new QLabel(tr("Decimal"));
    QLabel *hexLabel = new QLabel(tr("Hex"));
    QLabel *binLabel = new QLabel(tr("Binary"));
    decEdit = new QLineEdit;
    hexEdit = new QLineEdit;
    binEdit = new QLineEdit;
 
    editLayout->addWidget(decLabel,0,0);
    editLayout->addWidget(decEdit,0,1);
    editLayout->addWidget(hexLabel,1,0);
    editLayout->addWidget(hexEdit,1,1);
    editLayout->addWidget(binLabel,2,0);
    editLayout->addWidget(binEdit,2,1);
 
    QPushButton *exitButton = new QPushButton(tr("Quit"));
 
    buttonLayout->addStretch();
    buttonLayout->addWidget(exitButton);
 
    exitButton->setDefault(true);
 
    this->setWindowTitle("Byte Converter");
 
    QIntValidator* decValidator = new QIntValidator(0,255,decEdit);
    decEdit->setValidator(decValidator);
 
    QRegExpValidator* hexValidator = new QRegExpValidator(QRegExp("[0-9A-Fa-f]{1,2}"),hexEdit);
    hexEdit->setValidator(hexValidator);
 
    QRegExpValidator* binValidator = new QRegExpValidator(QRegExp("[01]{1,8}"),binEdit);
    binEdit->setValidator(binValidator);
 
    connect(exitButton,SIGNAL(clicked()),this,SLOT(close()));
    connect(decEdit,SIGNAL(textChanged(QString)),this,SLOT(decChanged(QString)));
    connect(hexEdit,SIGNAL(textChanged(QString)),this,SLOT(hexChanged(QString)));
    connect(binEdit,SIGNAL(textChanged(QString)),this,SLOT(binChanged(QString)));
}
 
void ByteConverterDialog::decChanged(const QString& newValue)
{
    bool ok;
    int num = newValue.toInt(&ok);
    if(ok)
    {
        hexEdit->setText(QString::number(num,16));
        binEdit->setText(QString::number(num,2));
    }
    else
    {
        hexEdit->setText("");
        binEdit->setText("");
    }
}
 
void ByteConverterDialog::hexChanged(const QString& newValue)
{
    bool ok;
    int num = newValue.toInt(&ok);
    if(ok)
    {
        decEdit->setText(QString::number(num));
        binEdit->setText(QString::number(num,2));
    }
    else
    {
        decEdit->setText("");
        binEdit->setText("");
    }
}
 
void ByteConverterDialog::binChanged(const QString& newValue)
{
    bool ok;
    int num = newValue.toInt(&ok);
    if(ok)
    {
        decEdit->setText(QString::number(num));
        hexEdit->setText(QString::number(num,16));
    }
    else
    {
        decEdit->setText("");
        hexEdit->setText("");
    }
}

#include <QLineEdit>
#include <QLabel>
#include <QPushButton>
#include <QVBoxLayout>
#include <QHBoxLayout>
#include <QGridLayout>
#include <QIntValidator>
#include <QRegExpValidator>
#include "ByteConverterDialog.h"

ByteConverterDialog::ByteConverterDialog()
{
    QVBoxLayout *mainLayout = new QVBoxLayout(this);
    QGridLayout *editLayout = new QGridLayout;
    QHBoxLayout *buttonLayout = new QHBoxLayout;

    mainLayout->addLayout(editLayout);
    mainLayout->addStretch();
    mainLayout->addLayout(buttonLayout);

    QLabel *decLabel = new QLabel(tr("Decimal"));
    QLabel *hexLabel = new QLabel(tr("Hex"));
    QLabel *binLabel = new QLabel(tr("Binary"));
    decEdit = new QLineEdit;
    hexEdit = new QLineEdit;
    binEdit = new QLineEdit;

    editLayout->addWidget(decLabel,0,0);
    editLayout->addWidget(decEdit,0,1);
    editLayout->addWidget(hexLabel,1,0);
    editLayout->addWidget(hexEdit,1,1);
    editLayout->addWidget(binLabel,2,0);
    editLayout->addWidget(binEdit,2,1);

    QPushButton *exitButton = new QPushButton(tr("Quit"));

    buttonLayout->addStretch();
    buttonLayout->addWidget(exitButton);

    exitButton->setDefault(true);

    this->setWindowTitle("Byte Converter");

    QIntValidator* decValidator = new QIntValidator(0,255,decEdit);
    decEdit->setValidator(decValidator);

    QRegExpValidator* hexValidator = new QRegExpValidator(QRegExp("[0-9A-Fa-f]{1,2}"),hexEdit);
    hexEdit->setValidator(hexValidator);

    QRegExpValidator* binValidator = new QRegExpValidator(QRegExp("[01]{1,8}"),binEdit);
    binEdit->setValidator(binValidator);

    connect(exitButton,SIGNAL(clicked()),this,SLOT(close()));
    connect(decEdit,SIGNAL(textChanged(QString)),this,SLOT(decChanged(QString)));
    connect(hexEdit,SIGNAL(textChanged(QString)),this,SLOT(hexChanged(QString)));
    connect(binEdit,SIGNAL(textChanged(QString)),this,SLOT(binChanged(QString)));
}

void ByteConverterDialog::decChanged(const QString& newValue)
{
    bool ok;
    int num = newValue.toInt(&ok);
    if(ok)
    {
        hexEdit->setText(QString::number(num,16));
        binEdit->setText(QString::number(num,2));
    }
    else
    {
        hexEdit->setText("");
        binEdit->setText("");
    }
}

void ByteConverterDialog::hexChanged(const QString& newValue)
{
    bool ok;
    int num = newValue.toInt(&ok);
    if(ok)
    {
        decEdit->setText(QString::number(num));
        binEdit->setText(QString::number(num,2));
    }
    else
    {
        decEdit->setText("");
        binEdit->setText("");
    }
}

void ByteConverterDialog::binChanged(const QString& newValue)
{
    bool ok;
    int num = newValue.toInt(&ok);
    if(ok)
    {
        decEdit->setText(QString::number(num));
        hexEdit->setText(QString::number(num,16));
    }
    else
    {
        decEdit->setText("");
        hexEdit->setText("");
    }
}

To copy to clipboard, switch view to plain text mode

main.cpp

Qt Code:

Switch view

#include <QApplication>
#include "ByteConverterDialog.h"
 
int main(int argc,char *argv[])
{
    QApplication app(argc,argv);
    ByteConverterDialog bc;
    bc.setAttribute(Qt::WA_QuitOnClose);
    bc.show();
    return app.exec();
}

#include <QApplication>
#include "ByteConverterDialog.h"

int main(int argc,char *argv[])
{
    QApplication app(argc,argv);
    ByteConverterDialog bc;
    bc.setAttribute(Qt::WA_QuitOnClose);
    bc.show();
    return app.exec();
}

To copy to clipboard, switch view to plain text mode

**Zlatomir** · 12th July 2010, 05:51

The only problem i see (at first look) is the textChanged() signal, that gets emited even when you don't want to, so use textEdited:

Qt Code:

Switch view

connect(decEdit,SIGNAL(textEdited(QString)),this,SLOT(decChanged(QString)));
//...

connect(decEdit,SIGNAL(textEdited(QString)),this,SLOT(decChanged(QString)));
//...

To copy to clipboard, switch view to plain text mode

LE: The textChanged() is emitted even when when your lineEdit is updated from modify in another lineEdit and you want the signal emitted only when the user writes in that lineEdit

**kumarpraveen** · 12th July 2010, 06:20

Originally Posted by Zlatomir

The only problem i see (at first look) is the textChanged() signal, that gets emited even when you don't want to, so use textEdited:

Qt Code:

Switch view

connect(decEdit,SIGNAL(textEdited(QString)),this,SLOT(decChanged(QString)));
//...

connect(decEdit,SIGNAL(textEdited(QString)),this,SLOT(decChanged(QString)));
//...

To copy to clipboard, switch view to plain text mode

LE: The textChanged() is emitted even when when your lineEdit is updated from modify in another lineEdit and you want the signal emitted only when the user writes in that lineEdit

Thanks a lot.

**Zlatomir** · 12th July 2010, 06:26

Another thing, use base 16 when convert from QString into int in hexChanged (because you will get empty string if you write FF or any "letter" in the hex lineEdit)

Qt Code:

Switch view

void ByteConverterDialog::hexChanged(const QString& newValue)
{
    bool ok;
    int num = newValue.toInt(&ok, 16);              // Here you need to use base 16
 
    if(ok)
    {
        decEdit->setText(QString::number(num));
        binEdit->setText(QString::number(num,2));
    }
    else
    {
        decEdit->setText("");
        binEdit->setText("");
    }
}

void ByteConverterDialog::hexChanged(const QString& newValue)
{
    bool ok;
    int num = newValue.toInt(&ok, 16);              // Here you need to use base 16

    if(ok)
    {
        decEdit->setText(QString::number(num));
        binEdit->setText(QString::number(num,2));
    }
    else
    {
        decEdit->setText("");
        binEdit->setText("");
    }
}

To copy to clipboard, switch view to plain text mode

**Zlatomir** · 12th July 2010, 06:34

Sorry for double post, but i found another little bug:
the same thing needs to be done with binChanged():

Qt Code:

Switch view

void ByteConverterDialog::binChanged(const QString& newValue)
{
    bool ok;
    int num = newValue.toInt(&ok, 2);      //use base 2 to get the results you want
    if(ok)
    {
        decEdit->setText(QString::number(num));
        hexEdit->setText(QString::number(num,16));
    }
//...
}

void ByteConverterDialog::binChanged(const QString& newValue)
{
    bool ok;
    int num = newValue.toInt(&ok, 2);      //use base 2 to get the results you want
    if(ok)
    {
        decEdit->setText(QString::number(num));
        hexEdit->setText(QString::number(num,16));
    }
//...
}

To copy to clipboard, switch view to plain text mode

**kumarpraveen** · 12th July 2010, 12:19

yeah you are right. Thanks

Thread: QLineEdit problem

Thread Tools

Search Thread

Display

QLineEdit problem

Re: QLineEdit problem

Re: QLineEdit problem

Re: QLineEdit problem

Re: QLineEdit problem

The following user says thank you to Zlatomir for this useful post:

Re: QLineEdit problem

Similar Threads

QLineEdit Problem

QLineEdit focus problem

problem with QLineEdit and QPalette

QLineEdit keyPressEvent problem

Problem with QLineEdit and setText

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions