Question

I keep getting this error:

cannot call member function 'QString Load::loadRoundsPlayed()'without object

Now im pretty new to c++ and qt so im not sure what this means. I am trying to call a function from another class to set the number on some lcdNumbers. Here is the Load.cpp which holds the function:

#include "load.h"
#include <QtCore>
#include <QFile>
#include <QDebug>

Load::Load() //here and down
{}

QString Load::loadRoundsPlayed()
{
    QFile roundsFile(":/StartupFiles/average_rounds.dat");

    if(!roundsFile.open(QFile::ReadOnly | QFile::Text))
    {
        qDebug("Could not open average_rounds for reading");
    }

    Load::roundsPlayed = roundsFile.readAll();
    roundsFile.close();
    return Load::roundsPlayed;
}

And here is the Load.h:

    #ifndef LOAD_H
     #define LOAD_H

    #include <QtCore>

    class Load
    {
    private:
        QString roundsPlayed; //and here
    public:
        Load();
        QString loadRoundsPlayed(); //and here
    };

    #endif // LOAD_H

And finally the place where i call the function:

    #include "mainwindow.h"
     #include "ui_mainwindow.h"
    #include "load.h"
    #include <QLCDNumber>

    MainWindow::MainWindow(QWidget *parent) :
        QMainWindow(parent),
        ui(new Ui::MainWindow)
    {
        ui->setupUi(this);
        MainWindow::startupLoad();
    }

    MainWindow::~MainWindow()
    {
        delete ui;
    }
    void MainWindow::startupLoad()
    {
        ui->roundPlayer_lcdNumber->display(Load::loadRoundsPlayed()); //right here
    }

When i run this i get that error. Im not sure what it means so if anyone could help i would be thankfull. Thanks.

Answer 1

The error description is pretty clear

cannot call member function ‘QString Load::loadRoundsPlayed()’without object

You cannot call member functions, that are not static, without creating instance of the class.

---

Looking at you code, you probably need to do this:

Load load;
ui->roundPlayer_lcdNumber->display(load.loadRoundsPlayed()); //right here

There are two other options:

• make loadRoundsPlayed static and roundsPlayed static, if you don’t want them to be associated with the concrete instances OR
• make loadRoundsPlayed static and return QString by copy, that will be locally created inside the function. Something like

:

QString Load::loadRoundsPlayed()
{
    QFile roundsFile(":/StartupFiles/average_rounds.dat");

    if(!roundsFile.open(QFile::ReadOnly | QFile::Text))
    {
        qDebug("Could not open average_rounds for reading");
    }

    QString lRoundsPlayed = roundsFile.readAll();
    roundsFile.close();
    return lRoundsPlayed;
}