Save object to a file

[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...

[Dmon]

https://www.dropbox.com/s/oal5r9sjtsmy42l/Qt stack.jpg

[Dmon]

https://www.dropbox.com/s/mosnz8o23elipn5/Qtstack.jpg

doesn't work with a space in the name

[SGaist]

Looks strange... Just to be on the safe side, delete the build directory completely and re-run your application.

[Dmon]

ok now it doesn't run again with a bunch of errors:

Running build steps for project Ass1Q1...
Configuration unchanged, skipping qmake step.
Starting: "C:/Qt/2010.04/mingw/bin/mingw32-make.exe" -w
mingw32-make: Entering directory C:/Unisa/COS3711/assignments/Ass1Q1-build-desktop' C:/Qt/2010.04/mingw/bin/mingw32-make -f Makefile.Debug mingw32-make[1]: Entering directory C:/Unisa/COS3711/assignments/Ass1Q1-build-desktop'
g++ -c -g -frtti -fexceptions -mthreads -Wall -DUNICODE -DQT_LARGEFILE_SUPPORT -DQT_DLL -DQT_GUI_LIB -DQT_CORE_LIB -DQT_THREAD_SUPPORT -DQT_NEEDS_QMAIN -I"........\Qt\2010.04\qt\include\QtCore" -I"........\Qt\2010.04\qt\include\QtGui" -I"........\Qt\2010.04\qt\include" -I"........\Qt\2010.04\qt\include\ActiveQt" -I"debug" -I"." -I"..\Ass1Q1" -I"." -I"........\Qt\2010.04\qt\mkspecs\win32-g++" -o debug\FilmWriter.o ..\Ass1Q1\FilmWriter.cpp
..\Ass1Q1\FilmWriter.cpp: In member function 'void FilmWriter::saveFilm(Film&)':
..\Ass1Q1\FilmWriter.cpp:10: error: no matching function for call to 'QFileDialog::getSaveFileName(FilmWriter* const, const char [10])'
........\Qt\2010.04\qt\include\QtGui/../../src/gui/dialogs/qfiledialog.h:216: note: candidates are: static QString QFileDialog::getSaveFileName(QWidget*, const QString&, const QString&, const QString&, QString*, QFlagsQFileDialog::Option)
..\Ass1Q1\FilmWriter.cpp:14: error: no matching function for call to 'QMessageBox::critical(FilmWriter* const, const char [6], const char [20])'
........\Qt\2010.04\qt\include\QtGui/../../src/gui/dialogs/qmessagebox.h:202: note: candidates are: static QMessageBox::StandardButton QMessageBox::critical(QWidget*, const QString&, const QString&, QFlagsQMessageBox::StandardButton, QMessageBox::StandardButton)
........\Qt\2010.04\qt\include\QtGui/../../src/gui/dialogs/qmessagebox.h:262: note: static int QMessageBox::critical(QWidget*, const QString&, const QString&, int, int, int)
........\Qt\2010.04\qt\include\QtGui/../../src/gui/dialogs/qmessagebox.h:265: note: static int QMessageBox::critical(QWidget*, const QString&, const QString&, const QString&, const QString&, const QString&, int, int)
........\Qt\2010.04\qt\include\QtGui/../../src/gui/dialogs/qmessagebox.h:272: note: static int QMessageBox::critical(QWidget*, const QString&, const QString&, QMessageBox::StandardButton, QMessageBox::StandardButton)
mingw32-make[1]: Leaving directory C:/Unisa/COS3711/assignments/Ass1Q1-build-desktop' mingw32-make: Leaving directory C:/Unisa/COS3711/assignments/Ass1Q1-build-desktop'
mingw32-make[1]: *** [debug/FilmWriter.o] Error 1
mingw32-make: *** [debug] Error 2
The process "C:/Qt/2010.04/mingw/bin/mingw32-make.exe" exited with code %2.
Error while building project Ass1Q1 (target: Desktop)
When executing build step 'Make'