Object::Connect problem

[geleven]

dear all,
i have some problem when make a connect function which is triggered when a QPushButton was clicked..
the error is

Object::connect: No such slot intervals::writeIntervals(4) in intervals.cpp:21

i give my QPushButton as "Ok", and this is my source code

source for my intervals.h :

#ifndef INTERVALS_H
#define INTERVALS_H
 
#include <QWidget>
#include <QTextStream>
#include <QFile>
#include <QIODevice>
 
namespace Ui {
    class intervals;
}
 
class intervals : public QWidget {
    Q_OBJECT
public:
    intervals(QWidget *parent = 0);
    ~intervals();
    QString readInterval();
    void writeInterval(int a);
 
protected:
    void changeEvent(QEvent *e);
 
private:
    Ui::intervals *ui;
    QString value;
 
public slots:
    void writeIntervals(int a);
 
};
 
#endif

#ifndef INTERVALS_H
#define INTERVALS_H

#include <QWidget>
#include <QTextStream>
#include <QFile>
#include <QIODevice>

namespace Ui {
    class intervals;
}

class intervals : public QWidget {
    Q_OBJECT
public:
    intervals(QWidget *parent = 0);
    ~intervals();
    QString readInterval();
    void writeInterval(int a);

protected:
    void changeEvent(QEvent *e);

private:
    Ui::intervals *ui;
    QString value;

public slots:
    void writeIntervals(int a);

};

#endif

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and intervals.cpp

#include "intervals.h"
#include "ui_intervals.h"
 
intervals::intervals(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::intervals)
{
    ui->setupUi(this);
    QFile file ("interval.txt");
    if (!file.exists("interval.txt"))
    {
        this->writeInterval(5);
        ui->IntervalEdit->setText(readInterval());
    }
    else
    {
        ui->IntervalEdit->setText(readInterval());
    }
 
    qDebug("tes");
    connect(ui->Ok,SIGNAL(clicked()),this,SLOT(writeIntervals(4)));
    qDebug("tes2");
}
 
void intervals::writeInterval(int a)
{
    QFile file("interval.txt");
    if (file.open(QIODevice::WriteOnly | QIODevice::Text))
    {
        QTextStream out(&file);
        out << a << "\n";
        file.close();
    }
}

#include "intervals.h"
#include "ui_intervals.h"

intervals::intervals(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::intervals)
{
    ui->setupUi(this);
    QFile file ("interval.txt");
    if (!file.exists("interval.txt"))
    {
        this->writeInterval(5);
        ui->IntervalEdit->setText(readInterval());
    }
    else
    {
        ui->IntervalEdit->setText(readInterval());
    }

    qDebug("tes");
    connect(ui->Ok,SIGNAL(clicked()),this,SLOT(writeIntervals(4)));
    qDebug("tes2");
}

void intervals::writeInterval(int a)
{
    QFile file("interval.txt");
    if (file.open(QIODevice::WriteOnly | QIODevice::Text))
    {
        QTextStream out(&file);
        out << a << "\n";
        file.close();
    }
}

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May someone help me with this error?

[Wysodava]

I'm not a QT expert, but I believe that you can not connect a signal to a slot unless they have the same function parameters.

http://doc.trolltech.com/4.6/signalsandslots.html

{
connect(ui->Ok,SIGNAL(clicked()),this,SLOT(writeIntervalFOUR( )));
}

void intervals::writeIntervalFOUR()
{
writeInterval(4);

}

Also look into QButtonGroup if you want the int parameter

[Lykurg]

You can't pass values inside a connect statement. But I guess a look at QSignalMapper could be worth for you.

[geleven]

You can't pass values inside a connect statement. But I guess a look at QSignalMapper could be worth for you.

oh ok... i see the problem. Thanks for your help, Lykurg and Wysodava