How do I get values from multiple QLineEdit into one matrix? - c++

Question

I'm quite new to QT, and I wanted to do the following:
Have a layout which initially consist of 1 QLineEdit (text) for input and 1 button for confirming it (button).
Then I wanted to send signal SetN(N) when the button is clicked and this signal should activate ArrayEdit(N) slot, which will change the layot to have N inputs (QLineEdit), and 1 button to send what's in them (as one array) to further processing .
I managed to do the first part, but... it didn't work and I don't know how to deal with this no matching member function error
Here's code of my class:
#include "textlayout.h"
TextLayout::TextLayout()
{
setWindowTitle("Choosing N value");
resize(200, 200);
auto layout = new QGridLayout(this);
auto text = new QLineEdit;
text->resize(10, 30);
auto button = new QPushButton();
button->setText("set");
layout->addWidget(text, 0, 0);
layout->addWidget(button, 0, 1);
QObject::connect(&button, SIGNAL(SetN())„ this, SLOT(ArrayEdit())); //no matching member function for call to 'connect'
int N = text->text().toInt();
if(N > 0)
{
emit SetN(N);
}
}
And its header file:
#ifndef TEXTLAYOUT_H
#define TEXTLAYOUT_H
#include <QWidget>
#include <QLineEdit>
#include <QLabel>
#include <QPushButton>
#include <QGridLayout>
#include <QObject>
class TextLayout : public QWidget
{
Q_OBJECT
public:
TextLayout();
public slots:
void ArrayEdit(int N);I
signals:
void SetN(int N);
};
#endif // TEXTLAYOUT_H
I know that actually now I don't activate this signal on click, but... well previously I didn't realize that and I don't know how to have sent parameter with onclick signal...
How can i work around it and how to fix this class?

Answer 1

you are not far away from doing it.. let me help you a little :)
TextLayout::TextLayout()
{
setWindowTitle("Choosing N value");
resize(200, 200);
/*auto*/ layout = new QGridLayout(this);
//declare layout in header, cos you will need it later in the slot
auto text = new QLineEdit;
text->resize(10, 30);
auto button = new QPushButton();
button->setText("set");
layout->addWidget(text, 0, 0);
layout->addWidget(button, 0, 1);
//QObject::connect(&button, SIGNAL(SetN())„ this, SLOT(ArrayEdit())); //no matching member function for call to 'connect'
//you dont need the QObject cos Textlayout is a QObject so just call connect:
connect(this, &TextLayout::SetN, this, &TextLayout::ArrayEdit);
//SetN is not a signal of QButton so you cant connect that like that... instead
connect(&button, &QPushButton::clicked, [this]()
{
int N = text->text().toInt();
if(N > 0)
{
emit SetN(N);
}
});
}

Answer 2

If you handle numeric values use QSpinBox instead of QLineEdit. Then you can also set limits and the user can't input invalid data.
Use QLineEdit for text.
Widget.hpp
#pragma once
#include <QWidget>
class QGridLayout;
class QLineEdit;
class QPushButton;
class QSpinBox;
class Widget : public QWidget
{
Q_OBJECT
public:
Widget(QWidget *parent = nullptr);
~Widget();
private slots:
void adjustLayout(int n);
private:
QGridLayout* _layout {};
QPushButton* _button {};
QSpinBox* _spinBox {};
QVector<QLineEdit*> _lineEditVector;
};
Widget.cpp
#include "Widget.hpp"
#include <QGridLayout>
#include <QLineEdit>
#include <QPushButton>
#include <QSpinBox>
Widget::Widget(QWidget *parent)
: QWidget(parent)
{
_layout = new QGridLayout(this);
_spinBox = new QSpinBox;
_button = new QPushButton("set");
_layout->addWidget(_spinBox, 0, 0);
_layout->addWidget(_button, 0, 1);
connect(_button, &QPushButton::clicked,
this, [this](bool) {
emit adjustLayout(_spinBox->value());
});
}
Widget::~Widget() = default;
void Widget::adjustLayout(int n)
{
for (int i=0; i<n; ++i)
{
QLineEdit* lineEdit = new QLineEdit(QString::number(i+1));
// for later access, keep a reference in the vector:
_lineEditVector.push_back(lineEdit);
_layout->addWidget(lineEdit, i + 1, 0);
}
}