Pointer Arrays

Pointer Arrays — arrays of pointers to any type of data, which grow automatically as new elements are added

Synopsis

#include <glib.h>

struct              GPtrArray;
GPtrArray *         g_ptr_array_new                     (void);
GPtrArray *         g_ptr_array_sized_new               (guint reserved_size);
GPtrArray *         g_ptr_array_new_with_free_func      (GDestroyNotify element_free_func);
GPtrArray *         g_ptr_array_new_full                (guint reserved_size,
                                                         GDestroyNotify element_free_func);
void                g_ptr_array_set_free_func           (GPtrArray *array,
                                                         GDestroyNotify element_free_func);
GPtrArray *         g_ptr_array_ref                     (GPtrArray *array);
void                g_ptr_array_unref                   (GPtrArray *array);
void                g_ptr_array_add                     (GPtrArray *array,
                                                         gpointer data);
void                g_ptr_array_insert                  (GPtrArray *array,
                                                         gint index_,
                                                         gpointer data);
gboolean            g_ptr_array_remove                  (GPtrArray *array,
                                                         gpointer data);
gpointer            g_ptr_array_remove_index            (GPtrArray *array,
                                                         guint index_);
gboolean            g_ptr_array_remove_fast             (GPtrArray *array,
                                                         gpointer data);
gpointer            g_ptr_array_remove_index_fast       (GPtrArray *array,
                                                         guint index_);
GPtrArray *         g_ptr_array_remove_range            (GPtrArray *array,
                                                         guint index_,
                                                         guint length);
void                g_ptr_array_sort                    (GPtrArray *array,
                                                         GCompareFunc compare_func);
void                g_ptr_array_sort_with_data          (GPtrArray *array,
                                                         GCompareDataFunc compare_func,
                                                         gpointer user_data);
void                g_ptr_array_set_size                (GPtrArray *array,
                                                         gint length);
#define             g_ptr_array_index                   (array,
                                                         index_)
gpointer *          g_ptr_array_free                    (GPtrArray *array,
                                                         gboolean free_seg);
void                g_ptr_array_foreach                 (GPtrArray *array,
                                                         GFunc func,
                                                         gpointer user_data);

Description

Pointer Arrays are similar to Arrays but are used only for storing pointers.

If you remove elements from the array, elements at the end of the array are moved into the space previously occupied by the removed element. This means that you should not rely on the index of particular elements remaining the same. You should also be careful when deleting elements while iterating over the array.

To create a pointer array, use g_ptr_array_new().

To add elements to a pointer array, use g_ptr_array_add().

To remove elements from a pointer array, use g_ptr_array_remove(), g_ptr_array_remove_index() or g_ptr_array_remove_index_fast().

To access an element of a pointer array, use g_ptr_array_index().

To set the size of a pointer array, use g_ptr_array_set_size().

To free a pointer array, use g_ptr_array_free().

An example using a GPtrArray:

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GPtrArray *array;
gchar *string1 = "one", *string2 = "two", *string3 = "three";

gparray = g_ptr_array_new ();
g_ptr_array_add (array, (gpointer) string1);
g_ptr_array_add (array, (gpointer) string2);
g_ptr_array_add (array, (gpointer) string3);

if (g_ptr_array_index (array, 0) != (gpointer) string1)
  g_print ("ERROR: got %p instead of %p\n",
           g_ptr_array_index (array, 0), string1);

g_ptr_array_free (array, TRUE);

Details

struct GPtrArray

struct GPtrArray {
  gpointer *pdata;
  guint	    len;
};

Contains the public fields of a pointer array.

gpointer *pdata;

points to the array of pointers, which may be moved when the array grows

guint len;

number of pointers in the array

g_ptr_array_new ()

GPtrArray *         g_ptr_array_new                     (void);

Creates a new GPtrArray with a reference count of 1.

Returns :

the new GPtrArray

g_ptr_array_sized_new ()

GPtrArray *         g_ptr_array_sized_new               (guint reserved_size);

Creates a new GPtrArray with reserved_size pointers preallocated and a reference count of 1. This avoids frequent reallocation, if you are going to add many pointers to the array. Note however that the size of the array is still 0.

reserved_size :

number of pointers preallocated

Returns :

the new GPtrArray

g_ptr_array_new_with_free_func ()

GPtrArray *         g_ptr_array_new_with_free_func      (GDestroyNotify element_free_func);

Creates a new GPtrArray with a reference count of 1 and use element_free_func for freeing each element when the array is destroyed either via g_ptr_array_unref(), when g_ptr_array_free() is called with free_segment set to TRUE or when removing elements.

element_free_func :

A function to free elements with destroy array or NULL. [allow-none]

Returns :

A new GPtrArray

Since 2.22


g_ptr_array_new_full ()

GPtrArray *         g_ptr_array_new_full                (guint reserved_size,
                                                         GDestroyNotify element_free_func);

Creates a new GPtrArray with reserved_size pointers preallocated and a reference count of 1. This avoids frequent reallocation, if you are going to add many pointers to the array. Note however that the size of the array is still 0. It also set element_free_func for freeing each element when the array is destroyed either via g_ptr_array_unref(), when g_ptr_array_free() is called with free_segment set to TRUE or when removing elements.

reserved_size :

number of pointers preallocated

element_free_func :

A function to free elements with destroy array or NULL. [allow-none]

Returns :

A new GPtrArray

Since 2.30


g_ptr_array_set_free_func ()

void                g_ptr_array_set_free_func           (GPtrArray *array,
                                                         GDestroyNotify element_free_func);

Sets a function for freeing each element when array is destroyed either via g_ptr_array_unref(), when g_ptr_array_free() is called with free_segment set to TRUE or when removing elements.

array :

A GPtrArray

element_free_func :

A function to free elements with destroy array or NULL. [allow-none]

Since 2.22


g_ptr_array_ref ()

GPtrArray *         g_ptr_array_ref                     (GPtrArray *array);

Atomically increments the reference count of array by one. This function is thread-safe and may be called from any thread.

array :

a GPtrArray

Returns :

The passed in GPtrArray

Since 2.22


g_ptr_array_unref ()

void                g_ptr_array_unref                   (GPtrArray *array);

Atomically decrements the reference count of array by one. If the reference count drops to 0, the effect is the same as calling g_ptr_array_free() with free_segment set to TRUE. This function is MT-safe and may be called from any thread.

array :

A GPtrArray

Since 2.22


g_ptr_array_add ()

void                g_ptr_array_add                     (GPtrArray *array,
                                                         gpointer data);

Adds a pointer to the end of the pointer array. The array will grow in size automatically if necessary.

array :

a GPtrArray

data :

the pointer to add

g_ptr_array_insert ()

void                g_ptr_array_insert                  (GPtrArray *array,
                                                         gint index_,
                                                         gpointer data);

Inserts an element into the pointer array at the given index. The array will grow in size automatically if necessary.

array :

a GPtrArray

index_ :

the index to place the new element at, or -1 to append

data :

the pointer to add.

Since 2.40


g_ptr_array_remove ()

gboolean            g_ptr_array_remove                  (GPtrArray *array,
                                                         gpointer data);

Removes the first occurrence of the given pointer from the pointer array. The following elements are moved down one place. If array has a non-NULL GDestroyNotify function it is called for the removed element.

It returns TRUE if the pointer was removed, or FALSE if the pointer was not found.

array :

a GPtrArray

data :

the pointer to remove

Returns :

TRUE if the pointer is removed, FALSE if the pointer is not found in the array

g_ptr_array_remove_index ()

gpointer            g_ptr_array_remove_index            (GPtrArray *array,
                                                         guint index_);

Removes the pointer at the given index from the pointer array. The following elements are moved down one place. If array has a non-NULL GDestroyNotify function it is called for the removed element.

array :

a GPtrArray

index_ :

the index of the pointer to remove

Returns :

the pointer which was removed

g_ptr_array_remove_fast ()

gboolean            g_ptr_array_remove_fast             (GPtrArray *array,
                                                         gpointer data);

Removes the first occurrence of the given pointer from the pointer array. The last element in the array is used to fill in the space, so this function does not preserve the order of the array. But it is faster than g_ptr_array_remove(). If array has a non-NULL GDestroyNotify function it is called for the removed element.

It returns TRUE if the pointer was removed, or FALSE if the pointer was not found.

array :

a GPtrArray

data :

the pointer to remove

Returns :

TRUE if the pointer was found in the array

g_ptr_array_remove_index_fast ()

gpointer            g_ptr_array_remove_index_fast       (GPtrArray *array,
                                                         guint index_);

Removes the pointer at the given index from the pointer array. The last element in the array is used to fill in the space, so this function does not preserve the order of the array. But it is faster than g_ptr_array_remove_index(). If array has a non-NULL GDestroyNotify function it is called for the removed element.

array :

a GPtrArray

index_ :

the index of the pointer to remove

Returns :

the pointer which was removed

g_ptr_array_remove_range ()

GPtrArray *         g_ptr_array_remove_range            (GPtrArray *array,
                                                         guint index_,
                                                         guint length);

Removes the given number of pointers starting at the given index from a GPtrArray. The following elements are moved to close the gap. If array has a non-NULL GDestroyNotify function it is called for the removed elements.

array :

a GPtrArray

index_ :

the index of the first pointer to remove

length :

the number of pointers to remove

Returns :

the array

Since 2.4


g_ptr_array_sort ()

void                g_ptr_array_sort                    (GPtrArray *array,
                                                         GCompareFunc compare_func);

Sorts the array, using compare_func which should be a qsort()-style comparison function (returns less than zero for first arg is less than second arg, zero for equal, greater than zero if irst arg is greater than second arg).

Note that the comparison function for g_ptr_array_sort() doesn't take the pointers from the array as arguments, it takes pointers to the pointers in the array.

This is guaranteed to be a stable sort since version 2.32.

array :

a GPtrArray

compare_func :

comparison function

g_ptr_array_sort_with_data ()

void                g_ptr_array_sort_with_data          (GPtrArray *array,
                                                         GCompareDataFunc compare_func,
                                                         gpointer user_data);

Like g_ptr_array_sort(), but the comparison function has an extra user data argument.

Note that the comparison function for g_ptr_array_sort_with_data() doesn't take the pointers from the array as arguments, it takes pointers to the pointers in the array.

This is guaranteed to be a stable sort since version 2.32.

array :

a GPtrArray

compare_func :

comparison function

user_data :

data to pass to compare_func

g_ptr_array_set_size ()

void                g_ptr_array_set_size                (GPtrArray *array,
                                                         gint length);

Sets the size of the array. When making the array larger, newly-added elements will be set to NULL. When making it smaller, if array has a non-NULL GDestroyNotify function then it will be called for the removed elements.

array :

a GPtrArray

length :

the new length of the pointer array

g_ptr_array_index()

#define             g_ptr_array_index(array,index_)

Returns the pointer at the given index of the pointer array.

This does not perform bounds checking on the given index_, so you are responsible for checking it against the array length.

array :

a GPtrArray

index_ :

the index of the pointer to return

Returns :

the pointer at the given index

g_ptr_array_free ()

gpointer *          g_ptr_array_free                    (GPtrArray *array,
                                                         gboolean free_seg);

Frees the memory allocated for the GPtrArray. If free_seg is TRUE it frees the memory block holding the elements as well. Pass FALSE if you want to free the GPtrArray wrapper but preserve the underlying array for use elsewhere. If the reference count of array is greater than one, the GPtrArray wrapper is preserved but the size of array will be set to zero.

If array contents point to dynamically-allocated memory, they should be freed separately if free_seg is TRUE and no GDestroyNotify function has been set for array.

array :

a GPtrArray

free_seg :

if TRUE the actual pointer array is freed as well

Returns :

the pointer array if free_seg is FALSE, otherwise NULL. The pointer array should be freed using g_free().

g_ptr_array_foreach ()

void                g_ptr_array_foreach                 (GPtrArray *array,
                                                         GFunc func,
                                                         gpointer user_data);

Calls a function for each element of a GPtrArray.

array :

a GPtrArray

func :

the function to call for each array element

user_data :

user data to pass to the function

Since 2.4