The compiler wont let me instanciate fileprocessor *p; in mainwindow.ccp but I am able to in any other class.
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :QMainWindow(parent),ui(new Ui::MainWindow)
{
fileprocessor *p;
ui->setupUi(this);
QObject::connect(ui->Open, SIGNAL(clicked()),
this,SLOT(on_action_Open_triggered()));
}
MainWindow::~MainWindow()
{
delete ui;
}
-mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QFile>
#include <QFileDialog>
#include <QTextStream>
#include <QStandardItemModel>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
I am given fileprocessor:undeclared identifier and p: undeclared identifier
#user4217633: Include fileprocessor.h in the mainwindow.cpp, not in mainwindow.h. There you need a forward declaration:
class fileprocessor; // Just this
You already have such a forward declaration, in fact:
namespace Ui {
class MainWindow;
}
Related
I am trying to download a txt file from a url in QT but i can't seem to make it work.
I am following this guide https://wiki.qt.io/Download_Data_from_URL. I implemented the filedownloader class exactly like it's made in the guide, but when i try to use it like specified in the guide I cannot make it work. I created a slot to be called when the download is finished, but if i try to call the downloader inside like the guide it says it is an undeclared identifier.
Does anyone know how to correctly implement this code?
this is the .cpp of my code
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "mainwindow.h"
#include <QStringList>
#include <QCoreApplication>
#include <QFile>
#include <QFileInfo>
#include <QList>
#include <QtNetwork/QNetworkReply>
#include <QStringList>
#include <QTimer>
#include <QUrl>
#include <QtNetwork/QNetworkAccessManager>
#include <QtNetwork/QNetworkRequest>
#include <filedownloader.h>
#include <iostream>
#include <QObject>
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
QUrl emiurl( "url of my file");
// call to the downloader class.In the guide it's made differently, but it doesn't work
FileDownloader emiload(emiurl,this);
//this connect links the end of the download with the textwriter slot
QObject::connect(&emiload, SIGNAL (downloaded()), this, SLOT (textwriter()));
}
>MainWindow::~MainWindow()
{
delete ui;
}
//slot needed to create the txt file from the downloaded one
void MainWindow::textwriter()
{
QByteArray emibyte;
emibyte=emiload->downloadedData(); //this line gives me error
QFile emifile("emi.txt");
emifile.open(QIODevice::WriteOnly);
std::cout << emibyte.size() << std::endl;
QDataStream out(&emifile);
out << emibyte;
std::cout << emifile.size() << std::endl;
}
Now here's the .h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include "filedownloader.h"
#include <QMainWindow>
#include <QtNetwork/QNetworkAccessManager>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();
private:
Ui::MainWindow *ui;
private slots:
void textwriter();
};
#endif // MAINWINDOW_H
To make the undeclared identifier go away and successfully compile, you need to add FileDownloader to the class' declaration. This way, it will be known throughout the class.
I chose to go with the approach that's usual in Qt, to declare a pointer to FileDownloader.
#pragma once // <--- this is supported by virtually any compiler today
#include <QMainWindow>
#include <QtNetwork/QNetworkAccessManager>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class FileDownloader; // <-- forward declaration is enough, but you can also #include "filedownloader.h"
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget* parent = nullptr);
~MainWindow();
private:
Ui::MainWindow* ui = nullptr;
FileDownloader* emiload = nullptr; // <--- the important line!
private slots:
void textwriter();
};
And then instantiate and call emiload in the constructor:
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
// create an instance of FileDownloader with "new".
emiload = new FileDownloader(QUrl("url of my file"), this);
// using member pointer connection available since Qt5
connect(emiload, &FileDownloader::downloaded, this, &MainWindow::textwriter);
}
I wrote a program to control device with serial port. It works fine but I'd like to seperate the class which would operate serial ports. I also want to have acess to buttons, comboboxes, etc. from this class.
Here are most important parts of code:
Serialsettings header:
#ifndef SERIALSETTINGS_H
#define SERIALSETTINGS_H
#include <QMainWindow>
#include <QSerialPort>
#include "mainwindow.h"
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class SerialSettings : public MainWindow
{
Q_OBJECT
public:
struct Settings
{
QString name;
qint32 baudRate;
QString stringBaudRate;
QSerialPort::DataBits dataBits;
QString stringDataBits;
QSerialPort::Parity parity;
QString stringParity;
QSerialPort::StopBits stopBits;
QString stringStopBits;
QSerialPort::FlowControl flowControl;
QString stringFlowControl;
};
explicit SerialSettings(QWidget *parent = nullptr);
~SerialSettings();
Settings settings() const;
signals:
private:
void fillPortsInfo();
void fillPortsParameters();
void updateSettings();
private:
Settings m_currentSettings;
};
#endif
Serialsettings source:
#include "serialsettings.h"
#include <QSerialPort>
#include <QSerialPortInfo>
#include "mainwindow.h"
#include "ui_mainwindow.h"
SerialSettings::SerialSettings(QWidget *parent)
: MainWindow(parent)
{
//some functions
}
mainwindow.h:
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QSerialPort>
//#include "serialsettings.h"
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class SerialSettings;
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
Ui::MainWindow *ui;
explicit MainWindow(QWidget *parent = nullptr);
~MainWindow();
// some code
};
#endif
mainwindow.cpp:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "serialsettings.h"
#include <QSerialPortInfo>
#include <QSerialPort>
#include <QString>
#include <QDebug>
#include <QTimer>
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
//some code
};
MainWindow::~MainWindow()
{
delete ui;
}
I don't have any error at this moment but it finishes with: The program has unexpectedly finished.
Could you help me please with this problem?
I don't get it.
loginview.h
#ifndef LOGINVIEW_H
#define LOGINVIEW_H
#include <QMainWindow>
#include <QDebug>
#include <QPushButton>
class LoginView : public QWidget
{
public:
QWidget *LoginViewSetup(QWidget * wdgMain);
public slots:
virtual void LogInUser();
virtual void CreateUser();
public:
QPushButton *logInBtn;
QPushButton *createBtn;
};
#endif // LOGINVIEW_H
loginview.cpp
#include "loginview.h"
QWidget *LoginView::LoginViewSetup(QWidget * wdgMain)
{
//some code
return wdgCenter;
}
void LoginView::LogInUser()
{
//some code
}
void LoginView::CreateUser()
{
//some code
}
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QDebug>
#include <loginview.h>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:
Ui::MainWindow *ui;
QWidget * wdgMain;
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
wdgMain = new QWidget(this);
LoginView LoginViewObj;
QWidget *wdgCenter = LoginViewObj.LoginViewSetup(wdgMain);
setCentralWidget( wdgMain );
connect(LoginViewObj.createBtn, SIGNAL (released()), &LoginViewObj, SLOT (CreateUser()));
}
MainWindow::~MainWindow()
{
delete ui;
}
Problem:
QObject::connect: No such slot QWidget::CreateUser() in
../proj/mainwindow.cpp:16
I tried to add Q_OBJECT to the loginview.h and then rebuild project with QMAKE. After that there is no warning about slot, but buttons still not active. Program don't jump to handle of the button in debug mode.
Please, help me to understand what's wrong? I have an object of another class LoginView and I pass this object as a reciever for a slot. Why it passes through my class and searches slot in QWidget?
I'm trying displaying widget 'widg' in layer on MainWindow after pushing 'pushButton_2' but I'm receive this error: "expected primary-expression before ')' token"
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "widg.h"
#include "ui_widg.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
QObject::connect(ui->pushButton_2, SIGNAL(clicked()), SLOT(slotPush2()));
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::slotPush2()
{
ui->verticalLayout_3->addWidget(widg);
}
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:
Ui::MainWindow *ui;
private slots:
void slotPush2();
};
#endif // MAINWINDOW_H
widg.h
#ifndef WIDG_H
#define WIDG_H
#include <QWidget>
namespace Ui {
class widg;
}
class widg : public QWidget
{
Q_OBJECT
public:
explicit widg(QWidget *parent = 0);
~widg();
private:
Ui::widg *ui;
};
#endif // WIDG_H
widg.cpp
#include "widg.h"
#include "ui_widg.h"
widg::widg(QWidget *parent) :
QWidget(parent),
ui(new Ui::widg)
{
ui->setupUi(this);
}
widg::~widg()
{
delete ui;
}
Please, help me, what is my mistake?
It's difficult to understand precisely what your intentions are, but perhaps you meant this:
void MainWindow::slotPush2()
{
ui->verticalLayout_3->addWidget(new widg(this));
}
This question should hopefully be easy to answer. I created a few buttons in my MainWindow using Qt Creator, and when I go to write the functions for the buttons, the compiler says they were not declared in this scope. What do I need to #include for these objects to be declared? The compiler error for the following would be 'baseDir' was not declared in this scope. baseDir is the objectName for a lineEdit in my window.
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include "ui_mainwindow.h"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
public slots:
void getDir();
void createProj();
private slots:
void on_findDir_clicked();
void on_create_clicked();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "functions.h"
#include <QtGui/QApplication>
#include <QFileDialog>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_findDir_clicked()
{
QString path;
path = QFileDialog::getOpenFileName(
this,
"Choose a file to open",
QString::null,
QString::null );
baseDir->setText( path );
}
The items you define in your .ui file are not added directly to your main window class, they are added to its ui membre.
Try with:
ui->baseDir->setText( path );
Look at the ui_mainwindow.h file that is generated during the build if you're curious.