g_list_append ()

GList *
g_list_append (GList *list,
               gpointer data);

Adds a new element on to the end of the list.

Note that the return value is the new start of the list, if list was empty; make sure you store the new value.

g_list_append() has to traverse the entire list to find the end, which is inefficient when adding multiple elements. A common idiom to avoid the inefficiency is to use g_list_prepend() and reverse the list with g_list_reverse() when all elements have been added.

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// Notice that these are initialized to the empty list.
GList *string_list = NULL, *number_list = NULL;

// This is a list of strings.
string_list = g_list_append (string_list, "first");
string_list = g_list_append (string_list, "second");

// This is a list of integers.
number_list = g_list_append (number_list, GINT_TO_POINTER (27));
number_list = g_list_append (number_list, GINT_TO_POINTER (14));

g_list_prepend ()

GList *
g_list_prepend (GList *list,
                gpointer data);

Prepends a new element on to the start of the list.

Note that the return value is the new start of the list, which will have changed, so make sure you store the new value.

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// Notice that it is initialized to the empty list.
GList *list = NULL;

list = g_list_prepend (list, "last");
list = g_list_prepend (list, "first");

Do not use this function to prepend a new element to a different element than the start of the list. Use g_list_insert_before() instead.

g_list_insert ()

GList *
g_list_insert (GList *list,
               gpointer data,
               gint position);

Inserts a new element into the list at the given position.

g_list_insert_before ()

GList *
g_list_insert_before (GList *list,
                      GList *sibling,
                      gpointer data);

Inserts a new element into the list before the given position.

g_list_insert_before_link ()

GList *
g_list_insert_before_link (GList *list,
                           GList *sibling,
                           GList *link_);

Inserts link_ into the list before the given position.

Since: 2.62

g_list_insert_sorted ()

GList *
g_list_insert_sorted (GList *list,
                      gpointer data,
                      GCompareFunc func);

Inserts a new element into the list, using the given comparison function to determine its position.

If you are adding many new elements to a list, and the number of new elements is much larger than the length of the list, use g_list_prepend() to add the new items and sort the list afterwards with g_list_sort().

g_list_remove ()

GList *
g_list_remove (GList *list,
               gconstpointer data);

Removes an element from a GList. If two elements contain the same data, only the first is removed. If none of the elements contain the data, the GList is unchanged.

g_list_remove_link ()

GList *
g_list_remove_link (GList *list,
                    GList *llink);

Removes an element from a GList, without freeing the element. The removed element's prev and next links are set to NULL, so that it becomes a self-contained list with one element.

This function is for example used to move an element in the list (see the example for g_list_concat()) or to remove an element in the list before freeing its data:

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list = g_list_remove_link (list, llink);
free_some_data_that_may_access_the_list_again (llink->data);
g_list_free (llink);

g_list_delete_link ()

GList *
g_list_delete_link (GList *list,
                    GList *link_);

Removes the node link_ from the list and frees it. Compare this to g_list_remove_link() which removes the node without freeing it.

g_list_remove_all ()

GList *
g_list_remove_all (GList *list,
                   gconstpointer data);

Removes all list nodes with data equal to data . Returns the new head of the list. Contrast with g_list_remove() which removes only the first node matching the given data.

g_list_free ()

void
g_list_free (GList *list);

Frees all of the memory used by a GList. The freed elements are returned to the slice allocator.

If list elements contain dynamically-allocated memory, you should either use g_list_free_full() or free them manually first.

It can be combined with g_steal_pointer() to ensure the list head pointer is not left dangling:

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GList *list_of_borrowed_things = …;  /<!-- -->* (transfer container) *<!-- -->/
g_list_free (g_steal_pointer (&list_of_borrowed_things));

g_list_free_full ()

void
g_list_free_full (GList *list,
                  GDestroyNotify free_func);

Convenience method, which frees all the memory used by a GList, and calls free_func on every element's data.

free_func must not modify the list (eg, by removing the freed element from it).

It can be combined with g_steal_pointer() to ensure the list head pointer is not left dangling ­— this also has the nice property that the head pointer is cleared before any of the list elements are freed, to prevent double frees from free_func :

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GList *list_of_owned_things = …;  /<!-- -->* (transfer full) (element-type GObject) *<!-- -->/
g_list_free_full (g_steal_pointer (&list_of_owned_things), g_object_unref);

Since: 2.28

g_clear_list ()

void
g_clear_list (GList **list_ptr,
              GDestroyNotify destroy);

Clears a pointer to a GList, freeing it and, optionally, freeing its elements using destroy .

list_ptr must be a valid pointer. If list_ptr points to a null GList, this does nothing.

[skip]

Since: 2.64

g_list_alloc ()

GList *
g_list_alloc (void);

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.

g_list_free_1 ()

void
g_list_free_1 (GList *list);

Frees one GList element, but does not update links from the next and previous elements in the list, so you should not call this function on an element that is currently part of a list.

It is usually used after g_list_remove_link().

g_list_length ()

guint
g_list_length (GList *list);

Gets the number of elements in a GList.

This function iterates over the whole list to count its elements. Use a GQueue instead of a GList if you regularly need the number of items. To check whether the list is non-empty, it is faster to check list against NULL.

g_list_copy ()

GList *
g_list_copy (GList *list);

Copies a GList.

Note that this is a "shallow" copy. If the list elements consist of pointers to data, the pointers are copied but the actual data is not. See g_list_copy_deep() if you need to copy the data as well.

g_list_copy_deep ()

GList *
g_list_copy_deep (GList *list,
                  GCopyFunc func,
                  gpointer user_data);

Makes a full (deep) copy of a GList.

In contrast with g_list_copy(), this function uses func to make a copy of each list element, in addition to copying the list container itself.

func , as a GCopyFunc, takes two arguments, the data to be copied and a user_data pointer. On common processor architectures, it's safe to pass NULL as user_data if the copy function takes only one argument. You may get compiler warnings from this though if compiling with GCC’s -Wcast-function-type warning.

For instance, if list holds a list of GObjects, you can do:

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another_list = g_list_copy_deep (list, (GCopyFunc) g_object_ref, NULL);

And, to entirely free the new list, you could do:

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g_list_free_full (another_list, g_object_unref);

Since: 2.34

g_list_reverse ()

GList *
g_list_reverse (GList *list);

Reverses a GList. It simply switches the next and prev pointers of each element.

g_list_sort ()

GList *
g_list_sort (GList *list,
             GCompareFunc compare_func);

Sorts a GList using the given comparison function. The algorithm used is a stable sort.

GCompareFunc ()

gint
(*GCompareFunc) (gconstpointer a,
                 gconstpointer b);

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.

g_list_insert_sorted_with_data ()

GList *
g_list_insert_sorted_with_data (GList *list,
                                gpointer data,
                                GCompareDataFunc func,
                                gpointer user_data);

Inserts a new element into the list, using the given comparison function to determine its position.

If you are adding many new elements to a list, and the number of new elements is much larger than the length of the list, use g_list_prepend() to add the new items and sort the list afterwards with g_list_sort().

Since: 2.10

g_list_sort_with_data ()

GList *
g_list_sort_with_data (GList *list,
                       GCompareDataFunc compare_func,
                       gpointer user_data);

Like g_list_sort(), but the comparison function accepts a user data argument.

GCompareDataFunc ()

gint
(*GCompareDataFunc) (gconstpointer a,
                     gconstpointer b,
                     gpointer user_data);

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.

g_list_concat ()

GList *
g_list_concat (GList *list1,
               GList *list2);

Adds the second GList onto the end of the first GList. Note that the elements of the second GList are not copied. They are used directly.

This function is for example used to move an element in the list. The following example moves an element to the top of the list:

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list = g_list_remove_link (list, llink);
list = g_list_concat (llink, list);

g_list_foreach ()

void
g_list_foreach (GList *list,
                GFunc func,
                gpointer user_data);

Calls a function for each element of a GList.

It is safe for func to remove the element from list , but it must not modify any part of the list after that element.

GFunc ()

void
(*GFunc) (gpointer data,
          gpointer user_data);

Specifies the type of functions passed to g_list_foreach() and g_slist_foreach().

g_list_first ()

GList *
g_list_first (GList *list);

Gets the first element in a GList.

g_list_last ()

GList *
g_list_last (GList *list);

Gets the last element in a GList.

g_list_previous()

#define             g_list_previous(list)

A convenience macro to get the previous element in a GList. Note that it is considered perfectly acceptable to access list->prev directly.

g_list_next()

#define             g_list_next(list)

A convenience macro to get the next element in a GList. Note that it is considered perfectly acceptable to access list->next directly.

g_list_nth ()

GList *
g_list_nth (GList *list,
            guint n);

Gets the element at the given position in a GList.

This iterates over the list until it reaches the n -th position. If you intend to iterate over every element, it is better to use a for-loop as described in the GList introduction.

g_list_nth_data ()

gpointer
g_list_nth_data (GList *list,
                 guint n);

Gets the data of the element at the given position.

This iterates over the list until it reaches the n -th position. If you intend to iterate over every element, it is better to use a for-loop as described in the GList introduction.

g_list_nth_prev ()

GList *
g_list_nth_prev (GList *list,
                 guint n);

Gets the element n places before list .

g_list_find ()

GList *
g_list_find (GList *list,
             gconstpointer data);

Finds the element in a GList which contains the given data.

g_list_find_custom ()

GList *
g_list_find_custom (GList *list,
                    gconstpointer data,
                    GCompareFunc func);

Finds an element in a GList, using a supplied function to find the desired element. It iterates over the list, calling the given function which should return 0 when the desired element is found. The function takes two gconstpointer arguments, the GList element's data as the first argument and the given user data.

g_list_position ()

gint
g_list_position (GList *list,
                 GList *llink);

Gets the position of the given element in the GList (starting from 0).

g_list_index ()

gint
g_list_index (GList *list,
              gconstpointer data);

Gets the position of the element containing the given data (starting from 0).

struct GList

struct GList {
  gpointer data;
  GList *next;
  GList *prev;
};

The GList struct is used for each element in a doubly-linked list.

g_list_free1

#define             g_list_free1

Another name for g_list_free_1().