Re: [gtk-list] glib: how to sort a doubly linked list?

[Eric Wong <egwong netcom com>]

Joel Wijngaarde wrote:
> 
> Hi
>  
> i noticed a function in glib called:
> 	GList* g_list_insert_sorted (GList *list, gpointer data,
> 				     GCompareFunc func)
[ cut ]

> Now i want to sort the GList alphabetically, looking at the 'name' in
> the data structure... Is there a way i can achieve this with the
> function above?

You could loop through the list with g_list_foreach(), copying
the data to a new list.  With a little work, something like
this ought to do.  One small problem is that the new list has
an empty element at the beginning (from g_list_alloc()) :(  I
can't think of a simple workaround.
  
   #include <gtk/gtk.h>      /* glib's somewhere in here */
   #include <string.h>       /* for strcmp */
   #include <stdio.h>        /* for printf */
   
   void
   print_data( gpointer data, gpointer user_data )
   {
     printf("%s\n", (char *)data);
   }
   
   int
   compare_func( gpointer a, gpointer b )
   {
     if ( a == NULL || b == NULL ) return 1;
   
     return strcmp( (char *)a, (char *)b );
   }
   
   void
   sort_glist( gpointer data, gpointer user_data )
   {
     if ( data == NULL ) return;
   
     g_list_insert_sorted( (GList *)user_data, data, &compare_func );
   }
   
   int
   main( int argc, char **argv )
   {
     GList            *glist_old;
     GList            *glist_new;
   
     glist_old = g_list_alloc();                           /* make list */
     glist_old->data = "foobar";
     g_list_append( glist_old, "joobar" );
     g_list_append( glist_old, "hoobar" );
     g_list_append( glist_old, "ioobar" );
     g_list_append( glist_old, "goobar" );
     g_list_foreach( glist_old, &print_data, NULL );
   
     printf("\n");
   
     glist_new = g_list_alloc();                           /* make new list */
     g_list_foreach( glist_old, &sort_glist, glist_new );  /* fill new list */
     g_list_foreach( glist_new, &print_data, NULL );
   
     g_list_free( glist_old );
   
     return 0;
   }