将结构传递给回调函数

Question

I'm trying to pass a struct to a callback function that runs when the combobox is changed, here's my code:

static struct parameters changed_set_parameters;

changed_set_parameters.set_combo = set_combo;

gtk_signal_connect (GTK_OBJECT (set_combo), "changed",GTK_SIGNAL_FUNC(set_changed), &changed_set_parameters);

Here's the function:

void set_changed(GtkDialog *dialog, gint response_id, gpointer callback_params) {
    g_print ("%s\n",gtk_combo_box_text_get_active_text ((GtkComboBoxText *)((struct parameters *) callback_params)->set_combo));
}

Here's what I get:

gtk_signal_handlers.h:7:98: error: dereferencing pointer to incomplete type
       g_print ("%s\n",gtk_combo_box_text_get_active_text ((GtkComboBoxText *)((struct parameters *) callback_params)->set_combo));

I have almost the same code in another application and it's running just fine

Answer 1

error: dereferencing pointer to incomplete type

这里的解除引用运算符->时，解除引用的指针是((struct parameters *) callback_params)其类型是struct parameters * ， set_combo是其成员的struct parameters ，从而定义struct parameters必须超出范围在这里。