arrays.sgml

This GLib version 2.16.1. GLib is the low-level core library that forms the basis for projects such

<!-- ##### SECTION Title ##### -->
Arrays

<!-- ##### SECTION Short_Description ##### -->
arrays of arbitrary elements which grow automatically as elements are added

<!-- ##### SECTION Long_Description ##### -->
<para>
Arrays are similar to standard C arrays, except that they grow automatically
as elements are added.
</para>
<para>
Array elements can be of any size (though all elements of one array are the
same size), and the array can be automatically cleared to '0's and
zero-terminated.
</para>
<para>
To create a new array use g_array_new().
</para>
<para>
To add elements to an array, use g_array_append_val(), g_array_append_vals(),
g_array_prepend_val(), and g_array_prepend_vals().
</para>
<para>
To access an element of an array, use g_array_index().
</para>
<para>
To set the size of an array, use g_array_set_size().
</para>
<para>
To free an array, use g_array_free().
</para>
<example>
<title>Using a <structname>GArray</structname> to store <type>gint</type> values</title>
<programlisting>
  GArray *garray;
  gint i;

  /* We create a new array to store gint values.
     We don't want it zero-terminated or cleared to 0's. */
  garray = g_array_new (FALSE, FALSE, sizeof (gint));
  for (i = 0; i &lt; 10000; i++)
    g_array_append_val (garray, i);

  for (i = 0; i &lt; 10000; i++)
    if (g_array_index (garray, gint, i) != i)
      g_print ("ERROR: got &percnt;d instead of &percnt;d\n",
               g_array_index (garray, gint, i), i);

  g_array_free (garray, TRUE);
</programlisting></example>

<!-- ##### SECTION See_Also ##### -->
<para>

</para>

<!-- ##### SECTION Stability_Level ##### -->


<!-- ##### STRUCT GArray ##### -->
<para>
Contains the public fields of an <link linkend="glib-arrays">Array</link>.
</para>

@data: a pointer to the element data. The data may be moved as elements are
added to the #GArray.
@len: the number of elements in the #GArray.

<!-- ##### FUNCTION g_array_new ##### -->
<para>
Creates a new #GArray.
</para>

@zero_terminated: %TRUE if the array should have an extra element at the end
which is set to 0.
@clear_: %TRUE if #GArray elements should be automatically cleared to 0
when they are allocated.
@element_size: the size of each element in bytes.
@Returns: the new #GArray.


<!-- ##### FUNCTION g_array_sized_new ##### -->
<para>
Creates a new #GArray with @reserved_size elements
preallocated. This avoids frequent reallocation, if you are going to
add many elements to the array. Note however that the size of the
array is still 0.
</para>

@zero_terminated: %TRUE if the array should have an extra element at the end with all bits cleared.
@clear_: %TRUE if all bits in the array should be cleared to 0 on allocation.
@element_size: size of each element in the array.
@reserved_size: number of elements preallocated.
@Returns: the new #GArray.


<!-- ##### MACRO g_array_append_val ##### -->
<para>
Adds the value on to the end of the array.
The array will grow in size automatically if necessary.
</para>
<note>
<para>
g_array_append_val() is a macro which uses a reference to the value
parameter @v. This means that you cannot use it with literal values
such as "27". You must use variables.
</para>
</note>

@a: a #GArray.
@v: the value to append to the #GArray.
@Returns: the #GArray.


<!-- ##### FUNCTION g_array_append_vals ##### -->
<para>
Adds @len elements onto the end of the array.
</para>

@array: a #GArray.
@data: a pointer to the elements to append to the end of the array.
@len: the number of elements to append.
@Returns: the #GArray.


<!-- ##### MACRO g_array_prepend_val ##### -->
<para>
Adds the value on to the start of the array.
The array will grow in size automatically if necessary.
</para>
<para>
This operation is slower than g_array_append_val() since the existing elements
in the array have to be moved to make space for the new element.
</para>
<note>
<para>
g_array_prepend_val() is a macro which uses a reference to the value
parameter @v. This means that you cannot use it with literal values
such as "27". You must use variables.
</para>
</note>

@a: a #GArray.
@v: the value to prepend to the #GArray.
@Returns: the #GArray.


<!-- ##### FUNCTION g_array_prepend_vals ##### -->
<para>
Adds @len elements onto the start of the array.
</para>
<para>
This operation is slower than g_array_append_vals() since the existing elements
in the array have to be moved to make space for the new elements.
</para>

@array: a #GArray.
@data: a pointer to the elements to prepend to the start of the array.
@len: the number of elements to prepend.
@Returns: the #GArray.


<!-- ##### MACRO g_array_insert_val ##### -->
<para>
Inserts an element into an array at the given index.
</para>
<note>
<para>
g_array_insert_val() is a macro which uses a reference to the value
parameter @v. This means that you cannot use it with literal values
such as "27". You must use variables.
</para>
</note>

@a: a #GArray.
@i: the index to place the element at.
@v: the value to insert into the array.
@Returns: the #GArray.


<!-- ##### FUNCTION g_array_insert_vals ##### -->
<para>
Inserts @len elements into a #GArray at the given index.
</para>

@array: a #GArray.
@index_: the index to place the elements at.
@data: a pointer to the elements to insert.
@len: the number of elements to insert.
@Returns: the #GArray.


<!-- ##### FUNCTION g_array_remove_index ##### -->
<para>
Removes the element at the given index from a #GArray.
The following elements are moved down one place.
</para>

@array: a #GArray.
@index_: the index of the element to remove.
@Returns: the #GArray.


<!-- ##### FUNCTION g_array_remove_index_fast ##### -->
<para>
Removes the element at the given index from a #GArray.
The last element in the array is used to fill in the space, so this function
does not preserve the order of the #GArray. But it is faster than
g_array_remove_index().
</para>

@array: a @GArray.
@index_: the index of the element to remove.
@Returns: the #GArray.


<!-- ##### FUNCTION g_array_remove_range ##### -->
<para>
Removes the given number of elements starting at the given index from a
#GArray.  The following elements are moved to close the gap.
</para>

@array: a @GArray.
@index_: the index of the first element to remove.
@length: the number of elements to remove.
@Returns: the #GArray.
@Since: 2.4


<!-- ##### FUNCTION g_array_sort ##### -->
<para>
Sorts a #GArray 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 zero if first arg is greater than second arg).
</para>
<para>
If two array elements compare equal, their order in the sorted array is
undefined.
</para>

@array: a #GArray.
@compare_func: comparison function.


<!-- ##### FUNCTION g_array_sort_with_data ##### -->
<para>
Like g_array_sort(), but the comparison function receives an extra user data
argument.
</para>

@array: a #GArray.
@compare_func: comparison function.
@user_data: data to pass to @compare_func.


<!-- ##### MACRO g_array_index ##### -->
<para>
Returns the element of a #GArray at the given index.
The return value is cast to the given type.

<example>
<title>Getting a pointer to an element in a <structname>GArray</structname></title>
<programlisting>
  EDayViewEvent *event;

  /* This gets a pointer to the 3rd element in the array of EDayViewEvent
     structs. */
  event = &amp;g_array_index (events, EDayViewEvent, 3);
</programlisting>
</example>
</para>

@a: a #GArray.
@t: the type of the elements.
@i: the index of the element to return.
@Returns: the element of the #GArray at the index given by @i.


<!-- ##### FUNCTION g_array_set_size ##### -->
<para>
Sets the size of the array, expanding it if necessary.
If the array was created with @clear_ set to %TRUE, the new elements are set to 0.
</para>

@array: a #GArray.
@length: the new size of the #GArray.
@Returns: the #GArray.


<!-- ##### FUNCTION g_array_free ##### -->
<para>
Frees the memory allocated for the #GArray.
If @free_segment is %TRUE it frees the memory block holding the elements
as well. Pass %FALSE if you want to free the #GArray wrapper but preserve
the underlying array for use elsewhere.
</para>
<note>
<para>
If array elements contain dynamically-allocated memory, they should be freed
separately.
</para>
</note>

@array: a #GArray.
@free_segment: if %TRUE the actual element data is freed as well.
@Returns: the element data if @free_segment is %FALSE, otherwise %NULL.
	The element data should be freed using g_free().