Dereferencing a String Vector in C++ when passing to GTK callback - c++

Question

I have this code which is trying to pass a vector to a callback function:
static void displayvecchoices( GtkWidget *widget, gpointer data ) {
std::vector<std::string> vecp = *(std::vector<std::string> *)(data);
std::cout<<"vec: "<<vecp[0]<<std::endl;
}
int main(int argc, char *argv[] ) {
GtkWidget *window;
GtkWidget *display;
gtk_init(&argc, &argv);
window = gtk_dialog_new ();
g_signal_connect (window, "destroy", G_CALLBACK (destroy), NULL);
gtk_window_fullscreen (GTK_WINDOW(window));
std::vector<std::string> vec;
vec.push_back("1");
display = gtk_button_new_with_label ("Display");
g_signal_connect_swapped (display, "clicked", G_CALLBACK (displayvecchoices), &vec);
gtk_widget_set_can_default (display, TRUE);
gtk_box_pack_start (GTK_BOX (GTK_DIALOG (window)->action_area), display, TRUE, TRUE, 0);
gtk_widget_grab_default (display);
gtk_widget_show (display);
gtk_main();
return 0;
}
When the button display is clicked, I get an error of 'bad alloc' and the program crashes.
When I try this:
std::vector<std::string>* vecp = (std::vector<std::string> *)(data);
std::cout<<"vec: "<<(*vecp)[0]<<std::endl;
It prints out vec: but no element and the size is said to be 18446744073706420840 of the vector.

Answer 1

It looks, your callback arguments are swapped:
you should either use g_signal_connect_object instead of g_signal_connect_swapped or
change displayvecchoices declaration to
static void displayvecchoices(gpointer data, GtkWidget *widget)