Save object to a file

[Dmon]

Yes it's an assignment I'm doing. I don't understand how it doesn't see it because saveFilm is a function in class FilmWriter which is included in class definition for class FilmInput which is has a function which calls saveFilm.

[SGaist]

Without the code it's difficult to comment

[Dmon]

@#ifndef FILM_H
#define FILM_H

#include <QWidget>
#include <QString>
#include <QDate>

class Film:public QWidget{
public:
Film(QString t,int dur,QString dir,QDate r);
Film();
void setTitle(QString t);
void setDuration(int dur);
void setDirector(QString dir);
void setReleaseDate(QDate r);
QString getTitle() const;
int getDuration() const;
QString getDirector() const;
QDate getReleaseDate() const;
QString toString();

private:
QString m_title;
int m_duration;
QString m_director;
QDate m_releaseDate;

};

#endif // FILM_H

#ifndef FILMWRITER_H
#define FILMWRITER_H
#include "Film.h"
#include <QtGui>
#include <QFile>

class FilmWriter: public Film{

public:
void saveFilm(Film& f);

};
#endif // FILMWRITER_H

#ifndef FILMINPUT_H
#define FILMINPUT_H

#include <QMainWindow>
#include "Film.h"
#include "FilmWriter.h"
#include <QLabel>
#include <QTextEdit>
#include <QPushButton>

namespace Ui {
class FilmInput;
}

class FilmInput : public QMainWindow
{
Q_OBJECT

public:
explicit FilmInput(QWidget parent = 0);
~FilmInput();
void obtainFilmData(Film& f);
void saveFilm(Film& f);
public slots:
void getFilm();
private:
Ui::FilmInput ui;
//widgets
QMainWindow window;
QLabel infoLabel;
QLabel* titleLabel;
QLabel* durationLabel;
QLabel* directorLabel;
QLabel* relDateLabel;
QTextEdit* titleEdit;
QTextEdit* durationEdit;
QTextEdit* directorEdit;
QTextEdit* relDateEdit;
QPushButton* saveBtn;
QPushButton* cancelBtn;
Film f;
//sets up gui and connects signals and slots
void setUpGui();
};

#endif // FILMINPUT_H

#include "Film.h"
#include <QDate>
#include <QString>

Film::Film(QString t,int dur,QString dir,QDate r):m_title(t),m_duration(dur),m_director(dir),m_releaseDate(r){

}

Film::Film(){
}

void Film::setTitle(QString t){
m_title = t;
}

void Film::setDuration(int dur){
m_duration = dur;
}

void Film::setDirector(QString dir){
m_director = dir;
}

void Film::setReleaseDate(QDate r){
m_releaseDate = r;
}

QString Film::getTitle() const{
return QString("%1").arg(m_title);
}

int Film::getDuration() const{
return m_duration;
}
QString Film::getDirector() const{
return QString("%1").arg(m_director);
}
QDate Film::getReleaseDate() const{
return m_releaseDate;
}
QString Film::toString()
{
return m_title + " " + m_duration + " " + m_director + " " + m_releaseDate.toString();
}

#include "FilmWriter.h"
#include <QtGui>
#include <QFileDialog>
#include <QFile>
#include <QMessageBox>
#include <QObject>
#include <QTextStream>

void FilmWriter::saveFilm(Film& f){
QString fileName = QFileDialog::getSaveFileName(this,("Save File"));
if (fileName != "") {
QFile file(fileName);
if (!file.open(QIODevice::WriteOnly)) {
QMessageBox::critical(this, ("Error"),("Could not open file"));// error message
} else {
QTextStream stream(&file);
stream << f.toString();
stream.flush();
file.close();
}
}

}

#include "filminput.h"
#include "ui_filminput.h"
#include <QtGui>
#include "Film.h"
#include "FilmWriter.h"
#include <QTextEdit>
#include <QDate>
#include <QString>

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

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

void FilmInput::setUpGui(){
//initialise widgets
infoLabel = new QLabel("Please enter film data which will be saved to a file",this);
titleLabel = new QLabel("Film Title",this);
durationLabel = new QLabel("Film Duration",this);
directorLabel = new QLabel("Film Director",this);
relDateLabel = new QLabel("Film Release Date",this);
titleEdit = new QTextEdit(this);
durationEdit = new QTextEdit(this);
directorEdit = new QTextEdit(this);
relDateEdit = new QTextEdit(this);
saveBtn = new QPushButton("Save Film",this);
cancelBtn = new QPushButton("Cancel",this);
//set layout
QFormLayout* layout = new QFormLayout();
layout->addWidget(infoLabel);
layout->addWidget(titleLabel);
layout->addWidget(titleEdit);
layout->addWidget(durationLabel);
layout->addWidget(durationEdit);
layout->addWidget(directorLabel);
layout->addWidget(directorEdit);
layout->addWidget(relDateLabel);
layout->addWidget(relDateEdit);
layout->addWidget(saveBtn);
layout->addWidget(cancelBtn);

this->ui->widget->setLayout(layout);
this->setWindowTitle("Film Archive");
connect(saveBtn,SIGNAL(clicked()),this, SLOT(getFilm()));
connect(cancelBtn,SIGNAL(clicked()),this,SLOT(close()));

}

void FilmInput::getFilm(){
Film f1(titleEdit->toPlainText(),durationEdit->toPlainText().toInt() ,directorEdit->toPlainText(),
QDate::fromString(relDateEdit->toPlainText(),"dd/MM/YYYY"));;
obtainFilmData(f1);
}

void FilmInput::obtainFilmData(Film &f){
saveFilm(f);
}

#include <QtGui/QApplication>
#include "filminput.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);

FilmInput w;
w.show();

return a.exec();

}
@

[SGaist]

saveFilm is not a member of FilmInput.

Besides that, please, got through the examples and the documentation of Qt, that would be beneficial to you.

I don't want to sound rude but what you wrote here will not do for an assignment.

Why does Film inherit QWidget ?
Why does FilmWriter inherit Film if it's only function is to write a Film given as a parameter ?
Why do you use a UI file if you create your interface by hand anyway ?

[Dmon]

I thought that FilmWriter would need to inherit Film in order to create an object of type Film. Film inheriting QWidget is a mistake as it is left over from the question which was one class called film inheriting QWidget which I have to break up into 3 classes and then add functionality. Also the UI file was created automatically for me with Qt creator. I will look up some info on interfaces. So the question is to have the saveFilm function in the filmWriter class, how do I get it to work like that rather than making saveFilm a member of FilmInput and removing the FilmWriter class?

[SGaist]

No it doesn't, as long as it knows how to use Film.

For the rest it's essentially doc reading

[Dmon]

if I take out #include "Film.h" in FilmWriter there is a problem with the FilmWriter class, if I then take out : public Film there is a problem with the func saveFilm because it's parameter is of type Film. So how do I make it know how to use Film?

[SGaist]

This is C/C++ basic knowledge. Without the header file how would your class know anything about Film ?

What problem would it be ?

[Dmon]

well it wouldn't know about Film without the header file. Are you saying that it doesn't need to be a child of Film but just include the header?

[SGaist]

Yes, it's exactly what I'm saying

[Dmon]

Ok great. But now after the changes I am still getting the same error :-?
:: error: collect2: ld returned 1 exit status

[SGaist]

If you are talking about the saveFilm problem and the message didn't changed, then saveFilm is still not a member of FilmInput.

Isn't it a member of FilmWriter ?

[Dmon]

Yes and I don't want it to be a member of FilmInput, I want it to be member of FilmWriter only and somehow (I don't know how) be called in FilmInput. I thought if I included the FilmWriter header it would work, but obviously I must do something else.

[SGaist]

FilmWriter is a class, how do you call a function from a class ?

[Dmon]

You create an object and call the function with the object. That's it! Ok so now you have helped me to get rid of that error, thanks a lot. Another question, when I click on the save film button which invokes saveFilm the program crashes, should I start a new thread because this is a new question or can you still help me on this one?

[SGaist]

Run your application through the debugger, it will tell you where the crash occurs

[Dmon]

I got this: The inferior stopped because it received a signal from the operating system
signal name: SIGSEGV
Signal meaning: Segmentation fault
then it is pointing to line 2185 in qglobal.h
inline QFlags operator&(Enum f) const { QFlags g; g.i = i & f; return g; }

[SGaist]

What does the stack trace look like ?
The lines under qglobal.h ?

[Dmon]

I have a print screen, how do I post a pic on here?

[SGaist]

You have to use a picture hosting service or a public dropbox folder etc...