Question

My friend and I have each created parts of a GUI using Qt 4. They both work independently and I am trying to integrate his form with the my main window. As of now this is the code I am using to try and load his form:

//connect buttons and such
connect(exitbtn, SIGNAL(triggered()),this,SLOT(terminated()));
connect(add, SIGNAL(triggered()),this,SLOT(add_rec()));

void MainWindowImpl::add_rec()
{
  //form quits as soon as it loads...?
  DialogImpl dia;//name of his form
  dia.show();
}

I have included his header file. The program compiles but when I hit the trigger his form loads up for maybe half a second and then closes. Does anyone know what I am doing wrong?

Answer 1

You have almost get it right. This is because the RAII of C++. If you allocate the Dialog on stack, it would be destructed as soon as the function return.

Answer 2

Assuming MainWindowImpl inherits publically from QWidget, you re looking for this:

void MainWindowImpl::add_rec() 
{
  // passing "this" to the constructor makes sure dialog will be cleaned up.
  // Note that DialogImpl will need a constructor that takes a
  // QObject* parent parameter.
  DialogImpl* dialog = new DialogImpl(this);

  dialog->show(); 
}

Look at the Qt documentation for examples of how the constructors should look.

Answer 3

Apparently QT4 only allows one instance of an object at a time, however pointers are another matter. Change both the main.cpp and what ever your main window to look something like this:

DialogImpl *dia=new DialogImpl;
dia->show();

友情链接