GTK+ example: handle "toggled" signal of RadioButton and determine the active selected RadioButton in group

This example implement radioButton_toggled() to handle the "toggled" signal from RadioButtons. Inside radioButton_toggled(), check if the button is active by calling gtk_toggle_button_get_active(), to determine the active selected RadioButton in group, then display on Label.

handle "toggled" signal of RadioButton

#include <gtk/gtk.h>

static void
radioButton_toggled (GtkWidget *button, GtkLabel  *label)
{
    char *button_state;
    const char *button_label = 
        gtk_button_get_label (GTK_BUTTON (button));

    if (gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (button))){
        button_state = "on";
        gtk_label_set_text (label, button_label);
    }
    else {
        button_state = "off";
    }

    g_print ("%s : %s\n", button_label, button_state);
}

int main( int argc, char *argv[])
{
    GtkWidget *window;
    GtkWidget *box;
    GtkWidget *label;

    GtkWidget *radioButton1;
    GtkWidget *radioButton2;
    GtkWidget *radioButton3;

    GtkWidget *radioButton4;
    GtkWidget *radioButton5;
    GSList *groupB;

    gtk_init(&argc, &argv);
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_default_size(GTK_WINDOW(window), 400, 250);
    gtk_window_set_title(GTK_WINDOW(window), "Linux-buddy.blogspot.com");
    box = gtk_box_new(GTK_ORIENTATION_VERTICAL, 5);

    label = gtk_label_new ("");
    gtk_box_pack_start(GTK_BOX(box), label, FALSE, FALSE, 3);

    //new RadioButton1, 2, 3 in same group
    radioButton1 = gtk_radio_button_new_with_label (
        NULL, "Radio Button 1");
    radioButton2 = gtk_radio_button_new_with_label_from_widget (
        GTK_RADIO_BUTTON (radioButton1), "Radio Button 2");
    radioButton3 = gtk_radio_button_new_with_label_from_widget (
        GTK_RADIO_BUTTON (radioButton1), "Radio Button 3");
    g_signal_connect (GTK_TOGGLE_BUTTON (radioButton1), "toggled", 
        G_CALLBACK (radioButton_toggled), label);
    g_signal_connect (GTK_TOGGLE_BUTTON (radioButton2), "toggled", 
        G_CALLBACK (radioButton_toggled), label);
    g_signal_connect (GTK_TOGGLE_BUTTON (radioButton3), "toggled", 
        G_CALLBACK (radioButton_toggled), label);
    gtk_box_pack_start(GTK_BOX(box), radioButton1, FALSE, FALSE, 3);
    gtk_box_pack_start(GTK_BOX(box), radioButton2, FALSE, FALSE, 3);
    gtk_box_pack_start(GTK_BOX(box), radioButton3, FALSE, FALSE, 3);

    //new RadioButton4, 5 in another group
    radioButton4 = gtk_radio_button_new_with_label (
        NULL, "Group B Button 4");
    groupB = gtk_radio_button_get_group (GTK_RADIO_BUTTON (radioButton4));
    radioButton5 = gtk_radio_button_new_with_label (
        groupB, "Group B Button 5");
    gtk_box_pack_start(GTK_BOX(box), radioButton4, FALSE, FALSE, 3);
    gtk_box_pack_start(GTK_BOX(box), radioButton5, FALSE, FALSE, 3);
    g_signal_connect (radioButton4, "toggled", 
        G_CALLBACK (radioButton_toggled), label);
    g_signal_connect (radioButton5, "toggled", 
        G_CALLBACK (radioButton_toggled), label);

    //Connects GCallback function gtk_main_quit to "destroy" signal for "window"
    g_signal_connect(G_OBJECT(window), "destroy", 
        G_CALLBACK(gtk_main_quit), NULL);

    gtk_container_add(GTK_CONTAINER(window), box);
    gtk_widget_show_all(window);
    gtk_main();

    return 0;
}