linked_lists_double.sgml

This GLib version 2.16.1. GLib is the low-level core library that forms the basis for projects such

<!-- ##### SECTION Title ##### -->
Doubly-Linked Lists

<!-- ##### SECTION Short_Description ##### -->
linked lists containing integer values or pointers to data, with the ability
to iterate over the list in both directions

<!-- ##### SECTION Long_Description ##### -->
<para>
The #GList structure and its associated functions provide a standard
doubly-linked list data structure.
</para>
<para>
Each element in the list contains a piece of data, together with pointers
which link to the previous and next elements in the list.
Using these pointers it is possible to move through the list in both
directions (unlike the
<link linkend="glib-Singly-Linked-lists">Singly-Linked Lists</link>
which only allows movement through the list in the forward direction).
</para>
<para>
The data contained in each element can be either integer values, by using one
of the
<link linkend="glib-Type-Conversion-Macros">Type Conversion Macros</link>,
or simply pointers to any type of data.
</para>
<para>
List elements are allocated from the <link linkend="glib-Memory-Slices">slice
allocator</link>, which is more efficient than allocating elements 
individually.
</para>
<para>
Note that most of the #GList functions expect to be passed a pointer to
the first element in the list. The functions which insert elements return
the new start of the list, which may have changed.
</para>
<para>
There is no function to create a #GList. %NULL is considered to be the empty
list so you simply set a #GList* to %NULL.
</para>
<para>
To add elements, use g_list_append(), g_list_prepend(), g_list_insert()
and g_list_insert_sorted().
</para>
<para>
To remove elements, use g_list_remove().
</para>
<para>
To find elements in the list use g_list_first(), g_list_last(), g_list_next(),
g_list_previous(), g_list_nth(), g_list_nth_data(), g_list_find() and
g_list_find_custom().
</para>
<para>
To find the index of an element use g_list_position() and g_list_index().
</para>
<para>
To call a function for each element in the list use g_list_foreach().
</para>
<para>
To free the entire list, use g_list_free().
</para>

<!-- ##### SECTION See_Also ##### -->
<para>

</para>

<!-- ##### SECTION Stability_Level ##### -->


<!-- ##### STRUCT GList ##### -->
<para>
The #GList struct is used for each element in a doubly-linked list.
</para>

@data: holds the element's data, which can be a pointer to any kind of data, 
  or any integer value using the
  <link linkend="glib-Type-Conversion-Macros">Type Conversion Macros</link>.
@next: contains the link to the next element in the list.
@prev: contains the link to the previous element in the list.

<!-- ##### FUNCTION g_list_append ##### -->
<para>

</para>

@list: 
@data: 
@Returns: 


<!-- ##### FUNCTION g_list_prepend ##### -->
<para>

</para>

@list: 
@data: 
@Returns: 


<!-- ##### FUNCTION g_list_insert ##### -->
<para>

</para>

@list: 
@data: 
@position: 
@Returns: 


<!-- ##### FUNCTION g_list_insert_before ##### -->
<para>

</para>

@list: 
@sibling: 
@data: 
@Returns: 


<!-- ##### FUNCTION g_list_insert_sorted ##### -->
<para>

</para>

@list: 
@data: 
@func: 
@Returns: 


<!-- ##### FUNCTION g_list_remove ##### -->
<para>

</para>

@list: 
@data: 
@Returns: 


<!-- ##### FUNCTION g_list_remove_link ##### -->
<para>

</para>

@list: 
@llink: 
@Returns: 


<!-- ##### FUNCTION g_list_delete_link ##### -->
<para>

</para>

@list: 
@link_: 
@Returns: 


<!-- ##### FUNCTION g_list_remove_all ##### -->
<para>

</para>

@list: 
@data: 
@Returns: 


<!-- ##### FUNCTION g_list_free ##### -->
<para>

</para>

@list: 


<!-- ##### FUNCTION g_list_alloc ##### -->
<para>
Allocates space for one #GList element.
It is called by g_list_append(), g_list_prepend(), g_list_insert() and
g_list_insert_sorted() and so is rarely used on its own.
</para>

@Returns: a pointer to the newly-allocated #GList element.


<!-- ##### FUNCTION g_list_free_1 ##### -->
<para>

</para>

@list: 


<!-- ##### MACRO g_list_free1 ##### -->
<para>
Another name for g_list_free_1().
</para>



<!-- ##### FUNCTION g_list_length ##### -->
<para>

</para>

@list: 
@Returns: 


<!-- ##### FUNCTION g_list_copy ##### -->
<para>

</para>

@list: 
@Returns: 


<!-- ##### FUNCTION g_list_reverse ##### -->
<para>

</para>

@list: 
@Returns: 


<!-- ##### FUNCTION g_list_sort ##### -->
<para>

</para>

@list: 
@compare_func: 
@Returns: 


<!-- ##### USER_FUNCTION GCompareFunc ##### -->
<para>
Specifies the type of a comparison function used to compare two
values.  The function should return a negative integer if the first
value comes before the second, 0 if they are equal, or a positive
integer if the first value comes after the second.
</para>

@a: a value.
@b: a value to compare with.
@Returns: negative value if @a &lt; @b; zero if @a = @b; positive value
if @a > @b.


<!-- ##### FUNCTION g_list_insert_sorted_with_data ##### -->
<para>

</para>

@list: 
@data: 
@func: 
@user_data: 
@Returns: 


<!-- ##### FUNCTION g_list_sort_with_data ##### -->
<para>

</para>

@list: 
@compare_func: 
@user_data: 
@Returns: 


<!-- ##### USER_FUNCTION GCompareDataFunc ##### -->
<para>
Specifies the type of a comparison function used to compare two
values.  The function should return a negative integer if the first
value comes before the second, 0 if they are equal, or a positive
integer if the first value comes after the second.
</para>

@a: a value.
@b: a value to compare with.
@user_data: user data to pass to comparison function.
@Returns: negative value if @a &lt; @b; zero if @a = @b; positive value
if @a > @b.


<!-- ##### FUNCTION g_list_concat ##### -->
<para>

</para>

@list1: 
@list2: 
@Returns: 


<!-- ##### FUNCTION g_list_foreach ##### -->
<para>

</para>

@list: 
@func: 
@user_data: 


<!-- ##### USER_FUNCTION GFunc ##### -->
<para>
Specifies the type of functions passed to g_list_foreach() and
g_slist_foreach().
</para>

@data: the element's data.
@user_data: user data passed to g_list_foreach() or g_slist_foreach().


<!-- ##### FUNCTION g_list_first ##### -->
<para>

</para>

@list: 
@Returns: 


<!-- ##### FUNCTION g_list_last ##### -->
<para>

</para>

@list: 
@Returns: 


<!-- ##### MACRO g_list_previous ##### -->
<para>
A convenience macro to gets the previous element in a #GList.
</para>

@list: an element in a #GList.
@Returns: the previous element, or %NULL if there are no previous elements.


<!-- ##### MACRO g_list_next ##### -->
<para>
A convenience macro to gets the next element in a #GList.
</para>

@list: an element in a #GList.
@Returns: the next element, or %NULL if there are no more elements.


<!-- ##### FUNCTION g_list_nth ##### -->
<para>

</para>

@list: 
@n: 
@Returns: 


<!-- ##### FUNCTION g_list_nth_data ##### -->
<para>

</para>

@list: 
@n: 
@Returns: 


<!-- ##### FUNCTION g_list_nth_prev ##### -->
<para>

</para>

@list: 
@n: 
@Returns: 



<para>

</para>


<!-- ##### FUNCTION g_list_find ##### -->
<para>

</para>

@list: 
@data: 
@Returns: 


<!-- ##### FUNCTION g_list_find_custom ##### -->
<para>

</para>

@list: 
@data: 
@func: 
@Returns: 


<!-- ##### FUNCTION g_list_position ##### -->
<para>

</para>

@list: 
@llink: 
@Returns: 


<!-- ##### FUNCTION g_list_index ##### -->
<para>

</para>

@list: 
@data: 
@Returns: 


<!-- ##### FUNCTION g_list_push_allocator ##### -->
<para>
Sets the allocator to use to allocate #GList elements.
Use g_list_pop_allocator() to restore the previous allocator.
</para>
<para>
Note that this function is not available if GLib has been compiled
with <option>--disable-mem-pools</option>
</para>

@allocator: the #GAllocator to use when allocating #GList elements.
@Deprecated: 2.10: It does nothing, since #GList has been
converted to the <link linkend="glib-Memory-Slices">slice allocator</link>


<!-- ##### FUNCTION g_list_pop_allocator ##### -->
<para>
Restores the previous #GAllocator, used when allocating #GList elements.
</para>
<para>
Note that this function is not available if GLib has been compiled
with <option>--disable-mem-pools</option>
</para>

@Deprecated: 2.10: It does nothing, since #GList has been
converted to the <link linkend="glib-Memory-Slices">slice allocator</link>