ANSI C compile error: expected expression before ‘,’ token

Question

I continue to get this error when attempting to compile a bit of code I wrote up, with the location in the file being totally unhelpful. This uses gtk 2.0.

The following is what I receive at compile time:

charles@draton-generico:~/Documents/C89$ gcc -x c -ansi -g bahbahbah.c -o bahbahbah pkg-config --cflags --libs gtk+-2.0

bahbahbah.c: In function ‘main’:

bahbahbah.c:28:1: error: expected expression before ‘,’ token

The following is the code I am trying to compile:

#include <stdio.h>
#include <stdlib.h>
#include <gtk/gtk.h>

#define EXIT_SUCCESS 0
#define EXIT_FAILURE 1

void closure(void)
{
    gtk_main_quit();
    printf("gtk_main_quit() has been called.\n");
}

void main(int argc, char* argv[])
{
    gboolean check = gtk_init_check(&argc, &argv);
    if (check == FALSE)
    {
        printf("Failed to initialize toolkit.\nTerminating.\n");
        exit(EXIT_FAILURE);
    }
    else
    {
        printf("Initialized toolkit.\n");
        GtkWidget* main_window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
        gtk_window_set_title((GtkWindow*)main_window, "BLAH");
        gtk_window_set_default_size((GtkWindow*)main_window, 700, 700);
        g_signal_connect(main_window, "delete-event", closure, void);
        gtk_widget_show(main_window);
        printf("Window created, sleeping in gtk_main().\n");
        gtk_main();
    }       
    printf("Exiting.\n");
    exit(EXIT_SUCCESS);
}

Please help. :(

Answer 1

Use NULL replace void in line 28.

g_signal_connect(main_window, "delete-event", closure, NULL);

Answer 2

void is a Key-word! There is the describe of g_signal_connect():

#define             g_signal_connect(instance, detailed_signal, c_handler, data)

Connects a GCallback function to a signal for a particular object.

The handler will be called before the default handler of the signal.

instance :
    the instance to connect to.

detailed_signal :
    a string of the form "signal-name::detail".

c_handler :
    the GCallback to connect.

data :
    data to pass to c_handler calls.

Returns :
    the handler id

So, you just want pass nothing to this func? Then you should use NULL.