程序界面：

这个就是一个用GTK+写的可视化的小例子。单击按钮就会实现+1或-1的操作。

代码如下：

#include <gtk/gtk.h>

gint count = 0;
char buf[5];

void increase(GtkWidget *widget, gpointer label)
{
    count++;
    sprintf(buf, "%d", count);
    gtk_label_set_text(label, buf);
}

void decrease(GtkWidget *widget, gpointer label)
{
    count--;
    sprintf(buf, "%d", count);
    gtk_label_set_text(label, buf);
}

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

    gtk_init(&argc, &argv);

    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
    gtk_window_set_default_size(GTK_WINDOW(window), 250, 180);
    gtk_window_set_title(GTK_WINDOW(window), "一个小例子");

    frame = gtk_fixed_new();
    gtk_container_add(GTK_CONTAINER(window), frame);

    plus = gtk_button_new_with_label("+1");
    gtk_widget_set_size_request(plus, 80, 35);
    gtk_fixed_put(GTK_FIXED(frame), plus, 50, 20);

    minus = gtk_button_new_with_label("-1");
    gtk_widget_set_size_request(minus, 80, 35);
    gtk_fixed_put(GTK_FIXED(frame), minus, 50, 80);

    label = gtk_label_new("0");
    gtk_fixed_put(GTK_FIXED(frame), label, 190, 58);

    gtk_widget_show_all(window);

    g_signal_connect(window, "destroy",G_CALLBACK(gtk_main_quit), NULL);
    g_signal_connect(plus, "clicked",G_CALLBACK(increase), label);
    g_signal_connect(minus, "clicked",G_CALLBACK(decrease), label);

    gtk_main();

    return 0;
}