c++ Gtkmm TextBuffer and TextView Segmentation fault

Question

I am learning c++ and Gtk+ GUI i am totally newbie and I can't find good tutorials, i have faced this problem so I will write a question here.

When i click on update button i get this error:

Segmentation fault

There is picture below explaining my problem.

---

Am i doing something wrong?

#include <iostream>
#include <gtkmm-3.0/gtkmm.h>

using namespace std;

Gtk::Window* window = 0;
Gtk::TextView* textview = 0;
Glib::RefPtr<Gtk::TextBuffer> text;
static void quit();
static void update();

int main(int argc, char *argv[])
{
    Glib::RefPtr<Gtk::Application> app = Gtk::Application::create(argc, argv, "org.gtkmm.example");

    //Load the GtkBuilder file and instantiate its widgets:
    Glib::RefPtr<Gtk::Builder> refBuilder = Gtk::Builder::create();
    try {
        refBuilder->add_from_file("window.glade");
    }

    catch(const Glib::FileError& ex) {
        std::cerr << "FileError: " << ex.what() << std::endl;
        return 1;
    }

    catch(const Glib::MarkupError& ex) {
        std::cerr << "MarkupError: " << ex.what() << std::endl;
        return 1;
    }

    catch(const Gtk::BuilderError& ex) {
        std::cerr << "BuilderError: " << ex.what() << std::endl;
        return 1;
    }

    //Get the GtkBuilder-instantiated Window:
    refBuilder->get_widget("window1", window);

    if(window) {

        window->set_title("GUI");
        window->set_size_request(600, 400);
        window->set_resizable(false);

        text = Gtk::TextBuffer::create();
        text->set_text("123");

        Gtk::Button* uButton = 0;
        refBuilder->get_widget("button2", uButton);
        if(uButton) {
            uButton->signal_clicked().connect(sigc::ptr_fun(update));
        }

        Gtk::Button* qButton = 0; // Quit button

        refBuilder->get_widget("button1", qButton);
        if(qButton) {
            qButton->signal_clicked().connect(sigc::ptr_fun(quit));
        }

        app->run(*window);
    }

    delete window;

    return 0;
}

static void quit() {
  if(window) window->hide(); //hide() will cause main::run() to end.
}

static void update() {
    textview->set_buffer(text);
}

Answer 1

You start with

Gtk::TextView* textview = 0;

Later you do:

textview->set_buffer(text);

Maybe I missed something but at no point I see you point textview at an actual textview object. I would expect something like:

 refBuilder->get_widget("???", textview );

during initialization.

Also you should use nullptr instead of 0. Or NULL assuming you do not use c++11