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Pointer Arrays

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

Types and Values

struct GPtrArray

Includes

#include <glib.h>

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";
gchar *string2 = "two";
gchar *string3 = "three";

array = 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);

Functions

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.

Parameters

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.

Parameters

element_free_func

A function to free elements with destroy array or NULL.

[nullable]

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.

Parameters

reserved_size

number of pointers preallocated

 

element_free_func

A function to free elements with destroy array or NULL.

[nullable]

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.

Parameters

array

A GPtrArray

 

element_free_func

A function to free elements with destroy array or NULL.

[nullable]

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.

Parameters

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 thread-safe and may be called from any thread.

Parameters

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.

Parameters

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.

Parameters

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.

Parameters

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.

Parameters

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.

Parameters

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.

Parameters

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.

Parameters

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.

Parameters

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.

Parameters

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.

Parameters

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.

Parameters

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 .

This function is not thread-safe. If using a GPtrArray from multiple threads, use only the atomic g_ptr_array_ref() and g_ptr_array_unref() functions.

Parameters

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.

Parameters

array

a GPtrArray

 

func

the function to call for each array element

 

user_data

user data to pass to the function

 

Since: 2.4


g_ptr_array_find ()

gboolean
g_ptr_array_find (GPtrArray *haystack,
                  gconstpointer needle,
                  guint *index_);

Checks whether needle exists in haystack . If the element is found, TRUE is returned and the element’s index is returned in index_ (if non-NULL). Otherwise, FALSE is returned and index_ is undefined. If needle exists multiple times in haystack , the index of the first instance is returned.

This does pointer comparisons only. If you want to use more complex equality checks, such as string comparisons, use g_ptr_array_find_with_equal_func().

[skip]

Parameters

haystack

pointer array to be searched

 

needle

pointer to look for

 

index_

return location for the index of the element, if found.

[optional][out caller-allocates]

Returns

TRUE if needle is one of the elements of haystack

Since: 2.54


g_ptr_array_find_with_equal_func ()

gboolean
g_ptr_array_find_with_equal_func (GPtrArray *haystack,
                                  gconstpointer needle,
                                  GEqualFunc equal_func,
                                  guint *index_);

Checks whether needle exists in haystack , using the given equal_func . If the element is found, TRUE is returned and the element’s index is returned in index_ (if non-NULL). Otherwise, FALSE is returned and index_ is undefined. If needle exists multiple times in haystack , the index of the first instance is returned.

equal_func is called with the element from the array as its first parameter, and needle as its second parameter. If equal_func is NULL, pointer equality is used.

[skip]

Parameters

haystack

pointer array to be searched

 

needle

pointer to look for

 

equal_func

the function to call for each element, which should return TRUE when the desired element is found; or NULL to use pointer equality.

[nullable]

index_

return location for the index of the element, if found.

[optional][out caller-allocates]

Returns

TRUE if needle is one of the elements of haystack

Since: 2.54

Types and Values

struct GPtrArray

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

Contains the public fields of a pointer array.

Members

gpointer *pdata;

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

 

guint len;

number of pointers in the array

 
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