GLib Reference Manual
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# Pointer Arrays

## Name

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);
    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_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);

## 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 1. Using a GPtrArray.

      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.

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. 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_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.

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.

`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().

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().

`array` : | a GPtrArray.
`index` : | the index of the pointer to remove.
Returns : | the pointer which was removed.

### 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 -1 for first arg is less than second arg, 0 for equal, 1 if first arg is greater than second arg).

`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 a user data argument.

`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, expanding it if necessary. New elements are set to `NULL`.

`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 all of the memory allocated for the pointer array.

`array` : | a GPtrArray.
`free_seg` : | if `TRUE` the actual element data is freed as well.
Returns : |

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