Pointer Arrays

## 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);
    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_);
    void                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.

### Note

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()`.

Example 22. Using a GPtrArray

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

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

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

    g_ptr_array_free (gparray, 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`.
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`.
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`.

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 MT-safe and may be called from any thread.

`array` : | A GArray.
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_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 ()

    void                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.

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).

If two array elements compare equal, their order in the sorted array is undefined. If you want equal elements to keep their order &8211; i.e. you want a stable sort &8211; you can write a comparison function that, if two elements would otherwise compare equal, compares them by their addresses.

### Note

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.

`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

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.

`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.

`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.

### Note

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