GLib Reference Manual | ||||
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Top | Description |
Pointer ArraysPointer Arrays — arrays of pointers to any type of data, which grow automatically as new elements are added |
#include <glib.h> 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
); 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
);
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()
.
Example 21. Using a GPtrArray
1 2 3 4 5 6 7 8 9 10 11 12 13 |
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); |
typedef struct { gpointer *pdata; guint len; } GPtrArray;
Contains the public fields of a pointer array.
GPtrArray* g_ptr_array_new (void
);
Creates a new GPtrArray with a reference count of 1.
Returns : |
the new GPtrArray. |
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.
|
number of pointers preallocated. |
Returns : |
the new GPtrArray. |
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.
|
A function to free elements with destroy array or NULL .
|
Returns : |
A new GPtrArray. |
Since 2.22
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.
Since 2.22
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.
Since 2.22
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.
|
A GPtrArray. |
Since 2.22
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.
|
a GPtrArray. |
|
the pointer to add. |
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.
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.
|
a GPtrArray. |
|
the index of the pointer to remove. |
Returns : |
the pointer which was removed. |
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.
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.
|
a GPtrArray. |
|
the index of the pointer to remove. |
Returns : |
the pointer which was removed. |
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.
|
a GPtrArray .
|
|
the index of the first pointer to remove. |
|
the number of pointers to remove. |
Since 2.4
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.
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.
|
a GPtrArray. |
|
comparison function. |
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.
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.
|
a GPtrArray. |
|
comparison function. |
|
data to pass to compare_func .
|
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.
|
a GPtrArray. |
|
the new length of the pointer array. |
#define g_ptr_array_index(array,index_)
Returns the pointer at the given index of the pointer array.
|
a GPtrArray. |
|
the index of the pointer to return. |
Returns : |
the pointer at the given index. |
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
.