Why Qt default project use separate header files for manwindow.cpp? - c++

I just created a Qt default project with a Qt designer form.
The class MainWindow is declared in a mainwindow.h and then included in mainwindows.cpp.
Why is it done this way ? Why not a declaration of this form directly in mainwindows.cpp ?:
class MainWindow
{
...
}
What is the proper way to add my code ? For example, a button that trigger a method.

In C++ you typically put class definitions into header files (.h), and method implementations in source files (.cpp). That allows clients of the class to use the class without having to see the implementation of each function. That also means that when adding a method, you'll typically have to make two changes: add the method to the class definition (in the header) and then add the method's implementation to the .CPP file.
In header file:
class MainWindow
{
void SomeMethod();
};
In source file:
void MainWindow::SomeMethod()
{
// Your code here.
}

The definition of MainWindow class is needed in another file, where an instance of it is constructed in the main function and then shown. That's why the class needs to be defined in a header file.
There are a number of ways to add your own code: for the button you described you could create in entirely in the QtCreator UI, or you could create it "programmatically" in the MainWindow constructor.

Related

How to add form to existing class?

I have an existing (QCreator build) class derived from QTextEdit
class CCC_MdiChild : public QTextEdit
I like to add GUI form like so
I have no issue creating new form.ui and adding it to the project.
I do not know how to modify existing constructor ( and its definition ) to include "form.ui" .
I am asking for an assistance / help to do that.
Here is my current constructor
Sorry , I did try to format the code but I could not "cut and paste " it as code .
( and I could not reedit it after it was edited once )
Since I did realize my poor formatting any automated comments in that aspect will be ....
The required steps are documented here. For completeness, they are:
Since you've added the .ui file to the project, the UI compiler should generate the corresponding header ui_form.h, which you should #include in the header for your class;
Add a private member to your class of the type defined in this header, which is in namespace Ui and takes its name from your .ui file;
Call the object's setup function as setupUi(this) in the constructor(s) of your class.
Alternatively, you also use multiple inheritance, or avoid including ui headers in header files with the slightly more complicated forward-declared pointer member approach.

wxWidgets - Splitting project into multiple files

I am very new to C++, I'm making this music application using wxWidgets, this is my first project in C++. As of now, I have 4 files, app.hpp and app.cpp which has a class that inherits from wxApp that launches the application, and frame.hpp and frame.cpp which holds the base frame and panel, and all the widgets, and their appropriate functions. I want to move all the functions to a separate file, but I get some errors like there is this function in frame.cpp
void Frame::ClearPlaylist(wxCommandEvent& event)
{
mediaCtrl->Stop();
playlistBox->Clear();
}
I tried moving it in another file called command.cpp and created a new class called command and prefixed all functions to Command:: .... and somethings like the playlistBox here, is a widget which I want in frame.cpp only, as it is a widget, so I did #include frame.hpp and prefixed it with Frame::playlistBox, but that gave a error saying invalid use of non static data member. So do I have to make everything in frame.hpp a static object? Or if anyone has a better solution for organizing a project like this please do share.

Are there any shortcut key to insert a definition of a function?

I use the Jetbrain's IDE Clion.
I want to insert a definition of a function whose forward declaration is already in header file to source file
For example,
I write foo.h file like this.
namespace sample{
class Foo{
void bar();
};
}
When I use the shortcut, I want to insert this to foo.cpp.
sample::Foo:bar(){}
Do you have any good suggestion?
Try this to implement your method :
// Definition of our method
void sample::Foo::bar()
{
// .....
}
Implement required methods :
On the Code menu, click Implement methods (Ctrl+I). Alternatively, you can right-click anywhere in the class file, then click Generate (Alt+Insert), and select Implement methods.

Shortcut to create C++ class method?

I have class definition code with function to be crated name
class CAAA
{
public:
public_method
}
I expect to create function stub in header and .cpp with help of some shortcut.
Trying to create class method in fast way:
Shortcut ctrl+1 brings No suggestions available:
Shortcut ctrl+space brings No Default proposal:
How to solve this problem?

Ui namespace in Qt widget projects

I have a Qt widget project called "SeasonCreator" and am wondering about the structure of a Qt widget project.
The ui_seasoncreator.h file is hidden, but when you look into it, it defines a namespace called "Ui" and in it is a declaration of a class SeasonCreator, which inherits from Ui_SeasonCreator, which is the c.
In the seasoncreator.h file, there is also a namespace called "Ui" also with a declaration of a class called "SeasonCreator". When I click to find its original declaration it leads me to the declaration of Ui::SeasonCreator in the ui_seasoncreator.h file.
What is the purpose for these namespace and classes? Do the two definitions relate?
Do any of these Ui::SeasonCreator declarations have anything to do with the custom SeasonCreator class in seasoncreator.h?
What is the purpose for these namespace and classes?
The code in ui_XXX.h is code that is automatically generated for you when you use designer to create a form. It's put into the Ui namespace.
Do the two definitions relate?
I'm assuming you're referring to something that looks like this:
namespace Ui { class SeasonCreator; }
which is a forward declaration of the class that is part of the generated code that gives your class access to the widgets in your custom form.
Do any of these Ui::SeasonCreator declarations have anything to do with the custom SeasonCreator class in seasoncreator.h?
It's what links your custom code together with the generated code. You should probably have a member variable of your custom class called Ui::SeasonCreator *ui, which is the object you use to access the generated Ui classes.