CODEWITHSUNDEEP
c++gladegtkmmsegmentation-fault
TimoL
TimoL

Reputation: 1

SIGSEGV on C++/Glade/gtkmm

I'm creating my first GUI application with C++ using gtkmm and Glade. I had to merge various tutorials, because none I found is supporting Glade in combination with Gtk::Application and various classes. See the code below:

main.cpp

int main(int argc, char **argv)
{
    std::cout << "Start" << std::endl;
    auto app = Gtk::Application::create(argc,argv,"org.gtkmm.ex");  
    auto builder = Gtk::Builder::create();
    builder->add_from_file("gui02.glade");

    HelloWorld* helloworld;
    std::cout << "helloworld compl." << std::endl;

    app->run(*helloworld);


    return 0;
}

helloworld.hpp

#include <gtkmm.h>

class HelloWorld : public Gtk::Window
{
protected:
    Glib::RefPtr<Gtk::Builder> builder;

    Gtk::Button *btn1;
    Gtk::Label *lb1;

public:
    HelloWorld(BaseObjectType* cobject, const Glib::RefPtr<Gtk::Builder>& refGlade);

protected:
    void on_button1_clicked();
};

helloworld.cpp

#include "helloworld.hpp"

using namespace std;
using namespace Gtk;

HelloWorld::HelloWorld(BaseObjectType* cobject, const Glib::RefPtr<Gtk::Builder>& refGlade) : 
    Gtk::Window(cobject), builder(refGlade)
{
    builder->get_widget("label1", lb1);
    builder->get_widget("button1", btn1);

    btn1->signal_clicked().connect(sigc::mem_fun(*this, &HelloWorld::on_button1_clicked));
}

void HelloWorld::on_button1_clicked()
{
    lb1->set_text("HW!");
}

Compiling using:

g++ main.cpp helloworld.cpp -o main `pkg-config gtkmm-3.0 --cflags --libs`

Result in the command line:

Start

helloworld compl.

Segmentation fault (core dumped)

Debugging with gdb (relevant extract, you get the full output if neccessary)

Glib::RefPtr::operator-> (this=0x7fffffffdd10) at /usr/include/glibmm-2.4/glibmm/refptr.h:260 260 return pCppObject_;

Thread 1 "main" received signal SIGSEGV, Segmentation fault.

0x00007ffff7a4799e in Gtk::Widget::signal_hide() () from /usr/lib/x86_64-linux-gnu/libgtkmm-3.0.so.1

Because I'm quite new to C++ (having some experience with C#), I'm not so used to pointers. Where is the error in this case?

Using a different code, where I create a Window* and use "app->run(*window)" works pretty fine, so the error occurs somewhere in the new app->run() and the outsourcing in class "HelloWorld".

Upvotes: 0

Views: 748

Answers (1)

al-eax
al-eax

Reputation: 732

Your code crashes here app->run(*helloworld); You try to dereference an empty pointer. That pointer does not point to an object in memory. Do it like this:

HelloWorld* helloworld = new HelloWorld();
std::cout << "helloworld compl." << std::endl;
app->run(*helloworld);

Upvotes: 0

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