1. Create open_link_example.c

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

void open_link(GtkButton *button, gpointer user_data) {
    const gchar *url = "https://example.com";
    GError *error = NULL;

    gtk_show_uri_on_window(NULL, url, GDK_CURRENT_TIME, &error);

    if (error != NULL) {
        g_warning("Failed to open link: %s", error->message);
        g_error_free(error);
    }
}

int main(int argc, char *argv[]) {
    gtk_init(&argc, &argv);

    GtkWidget *window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title(GTK_WINDOW(window), "Open Link Example");
    gtk_window_set_default_size(GTK_WINDOW(window), 400, 200);
    g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);

    GtkWidget *button = gtk_button_new_with_label("Open Link");
    g_signal_connect(button, "clicked", G_CALLBACK(open_link), NULL);
    gtk_container_add(GTK_CONTAINER(window), button);

    gtk_widget_show_all(window);

    gtk_main();

    return EXIT_SUCCESS;
}

2. Compile it

gcc -o open_link_example open_link_example.c `pkg-config --cflags --libs gtk+-3.0`

3. Run

./open_link_example