How to Login to my FTP Account

rezaMSLM

I'm a newbie in Qt (and poor English);
i have made a new project in Qt and want to include QFtp to my project but i dont know where i have to write "#include <QtNetwork/QFtp>"!! (in main.cpp or mainwindow.cpp file??)

SGaist

Where you will use an object that class.

rezaMSLM

@SGaist

i want to have a "Login" button in my GUI and login to my account when i press that.
so i have to include QFtp class in "mainwindow.cpp" .

Now i want to create new QFtp object with this command:
QFtp *ftp=new Qftp();
but i receive this error:

expected type-specifier before 'Qftp'
QFtp *ftp=new Qftp();

jsulm

@rezaMSLM It is QFtp not Qftp...

rezaMSLM

my mainwindow.cpp contents:

#include "ui_mainwindow.h"
#include <QtNetwork/QFtp>

QFtp *ftp=new QFtp();

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)

{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{

}

and my 3 Errors:
In function `_static_initialization_and_destruction_0':

undefined reference to `_imp___ZN4QFtpC1EP7QObject'

error: ld returned 1 exit status

jsulm

@rezaMSLM said in How to Login to my FTP Account:

QFtp *ftp=new QFtp();

This is bad!
Don't do this with Qt classes.
ftp should be class member in your MainWindow class.

rezaMSLM

@jsulm said in How to Login to my FTP Account:

@rezaMSLM said in How to Login to my FTP Account:

QFtp *ftp=new QFtp();

This is bad!
Don't do this with Qt classes.
ftp should be class member in your MainWindow class.

would you please correct my above Code?

jsulm

@rezaMSLM

// In your header file
class MainWindow...
private:
    QFtp ftp;
}

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

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{

}

rezaMSLM

my header file:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>


namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

/*added Code:*/
private:
    QFtp ftp;
/***********/
public:
    explicit MainWindow(QWidget *parent = 0);

    ~MainWindow();

private slots:
    void on_pushButton_clicked();

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

my Errors:
'QFtp' does not name a type
QFtp ftp;
^

jsulm

@rezaMSLM Didn't you forget to include the header file?

rezaMSLM

@jsulm said in How to Login to my FTP Account:

@rezaMSLM Didn't you forget to include the header file?

No,
my mainwindow.h file content:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>


namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

/*added Code:*/
private:
    QFtp ftp;
/***********/
public:
    explicit MainWindow(QWidget *parent = 0);

    ~MainWindow();

private slots:
    void on_pushButton_clicked();

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

main.cpp:

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


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtNetwork/QFtp>

//QFtp *ftp=new QFtp();

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)

{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{

}

.pro contents:

#-------------------------------------------------
#
# Project created by QtCreator 2018-02-28T21:06:27
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = ftp2
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0


SOURCES += \
        main.cpp \
        mainwindow.cpp

HEADERS += \
        mainwindow.h

FORMS += \
        mainwindow.ui

jsulm

@rezaMSLM You did forget.
You're using QFtp class now in your header file, so you need to move

#include <QtNetwork/QFtp>

to the header file, else compiler has no idea what QFtp is.

rezaMSLM

@jsulm said in How to Login to my FTP Account:

@rezaMSLM You did forget.
You're using QFtp class now in your header file, so you need to move
#include <QtNetwork/QFtp>
to the header file, else compiler has no idea what QFtp is.

now i have moved it to mainwindow.h
doesn't solved and here are the errors:

jsulm

@rezaMSLM Do you have this in your pro file:

QT += ftp

You do not link your app against QFtp currently.
Here is an example: https://github.com/qt/qtftp/tree/master/examples/qftp

rezaMSLM

@jsulm said in How to Login to my FTP Account:

@rezaMSLM Do you have this in your pro file:
QT += ftp
You do not link your app against QFtp currently.
Here is an example: https://github.com/qt/qtftp/tree/master/examples/qftp

Thank you jsulm;
QT+=ftp didnt work
but QT+=network worked!
Now i receive No Error

rezaMSLM

I built an object in mainwindow.h file using this command:

class MainWindow...
private:
    QFtp *ftp;
}

and call these commands when clicking on "Login" Button:

void MainWindow::on_pushButton_clicked()
{
    ftp->connectToHost("my Host IP");
    ftp->login("my user name" , "my password");
}

and when I Run the project and click on Login button it crashes.

but if i change the code like this it won't crash:

class MainWindow...
private:
    QFtp ftp;
}

void MainWindow::on_pushButton_clicked()
{
    ftp.connectToHost("my Host IP");
    ftp.login("my user name" , "my password");
}

why?

jsulm

@rezaMSLM Because if you use a pointer you need to create an instance and assign the pointer, else you're using a dangling pointer (a pointer not pointing to a valid chunk of memory). You should read about memory management in C/C++.

MainWindow::MainWindow()
{
    ftp = new QFtp();
}

Why do you want to use a pointer?

rezaMSLM

@jsulm I even don't know when I have to use pointer and when not!!!

rezaMSLM

when I click on login button and connectToHost() Command is executed how I notice that it's connected?
I know that some signals are emitted but i dont know how to use them

jsulm

@rezaMSLM

MainWindow::MainWindow()
{
    connect(&ftp, SIGNAL(stateChanged(int)), this, SLOT(checkState(int)));
}

void MainWindow::checkState(int state)
{
    switch(state) {
    case QFtp::Connected:
        break;
    ...
    }
}

// From QFtp header file:
enum State {
        Unconnected,
        HostLookup,
        Connecting,
        Connected,
        LoggedIn,
        Closing
};