array.tex

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\func{}{WX\_DECLARE\_OBJARRAY}{\param{}{T}, \param{}{name}}

\func{}{WX\_DECLARE\_EXPORTED\_OBJARRAY}{\param{}{T}, \param{}{name}}

\func{}{WX\_DECLARE\_USER\_EXPORTED\_OBJARRAY}{\param{}{T}, \param{}{name}}

This macro declares a new object array class named {\it name} and containing
the elements of type {\it T}. The second form is used when compiling wxWidgets as
a DLL under Windows and array needs to be visible outside the DLL.  The third is
needed for exporting an array from a user DLL.

Example:

\begin{verbatim}
class MyClass;
WX_DECLARE_OBJARRAY(MyClass, wxArrayOfMyClass); // note: not "MyClass *"!
\end{verbatim}

You must use \helpref{WX\_DEFINE\_OBJARRAY()}{wxdefineobjarray} macro to define
the array class - otherwise you would get link errors.

\membersection{WX\_DEFINE\_OBJARRAY}\label{wxdefineobjarray}

\func{}{WX\_DEFINE\_OBJARRAY}{\param{}{name}}

\func{}{WX\_DEFINE\_EXPORTED\_OBJARRAY}{\param{}{name}}

\func{}{WX\_DEFINE\_USER\_EXPORTED\_OBJARRAY}{\param{}{name}}

This macro defines the methods of the array class {\it name} not defined by the
\helpref{WX\_DECLARE\_OBJARRAY()}{wxdeclareobjarray} macro. You must include the
file <wx/arrimpl.cpp> before using this macro and you must have the full
declaration of the class of array elements in scope! If you forget to do the
first, the error will be caught by the compiler, but, unfortunately, many
compilers will not give any warnings if you forget to do the second - but the
objects of the class will not be copied correctly and their real destructor will
not be called.  The latter two forms are merely aliases of the first to satisfy
some people's sense of symmetry when using the exported declarations.

Example of usage:

\begin{verbatim}
// first declare the class!
class MyClass
{
public:
   MyClass(const MyClass&);

   ...

   virtual ~MyClass();
};

#include <wx/arrimpl.cpp>
WX_DEFINE_OBJARRAY(wxArrayOfMyClass);
\end{verbatim}

\membersection{WX\_APPEND\_ARRAY}\label{wxappendarray}

\func{void}{WX\_APPEND\_ARRAY}{\param{wxArray\& }{array}, \param{wxArray\& }{other}}

This macro may be used to append all elements of the {\it other} array to the
{\it array}. The two arrays must be of the same type.

\membersection{WX\_PREPEND\_ARRAY}\label{wxprependarray}

\func{void}{WX\_PREPEND\_ARRAY}{\param{wxArray\& }{array}, \param{wxArray\& }{other}}

This macro may be used to prepend all elements of the {\it other} array to the
{\it array}. The two arrays must be of the same type.

\membersection{WX\_CLEAR\_ARRAY}\label{wxcleararray}

\func{void}{WX\_CLEAR\_ARRAY}{\param{wxArray\& }{array}}

This macro may be used to delete all elements of the array before emptying it.
It can not be used with wxObjArrays - but they will delete their elements anyhow
when you call Empty().

\membersection{Default constructors}\label{wxarrayctordef}

\func{}{wxArray}{\void}

\func{}{wxObjArray}{\void}

Default constructor initializes an empty array object.

\func{}{wxSortedArray}{\param{int (*)(T first, T second)}{compareFunction}}

There is no default constructor for wxSortedArray classes - you must initialize it
with a function to use for item comparison. It is a function which is passed
two arguments of type {\it T} where {\it T} is the array element type and which
should return a negative, zero or positive value according to whether the first
element passed to it is less than, equal to or greater than the second one.

\membersection{wxArray copy constructor and assignment operator}\label{wxarrayctorcopy}

\func{}{wxArray}{\param{const wxArray\& }{array}}

\func{}{wxSortedArray}{\param{const wxSortedArray\& }{array}}

\func{}{wxObjArray}{\param{const wxObjArray\& }{array}}

\func{wxArray\&}{operator$=$}{\param{const wxArray\& }{array}}

\func{wxSortedArray\&}{operator$=$}{\param{const wxSortedArray\& }{array}}

\func{wxObjArray\&}{operator$=$}{\param{const wxObjArray\& }{array}}

The copy constructors and assignment operators perform a shallow array copy
(i.e. they don't copy the objects pointed to even if the source array contains
the items of pointer type) for wxArray and wxSortedArray and a deep copy (i.e.
the array element are copied too) for wxObjArray.

\membersection{wxArray::\destruct{wxArray}}\label{wxarraydtor}

\func{}{\destruct{wxArray}}{\void}

\func{}{\destruct{wxSortedArray}}{\void}

\func{}{\destruct{wxObjArray}}{\void}

The wxObjArray destructor deletes all the items owned by the array. This is not
done by wxArray and wxSortedArray versions - you may use
\helpref{WX\_CLEAR\_ARRAY}{wxcleararray} macro for this.

\membersection{wxArray::Add}\label{wxarrayadd}

\func{void}{Add}{\param{T }{item}, \param{size\_t}{ copies = $1$}}

\func{void}{Add}{\param{T *}{item}}

\func{void}{Add}{\param{T \&}{item}, \param{size\_t}{ copies = $1$}}

Appends the given number of {\it copies} of the {\it item} to the array
consisting of the elements of type {\it T}.

The first version is used with wxArray and wxSortedArray. The second and the
third are used with wxObjArray. There is an important difference between
them: if you give a pointer to the array, it will take ownership of it, i.e.
will delete it when the item is deleted from the array. If you give a reference
to the array, however, the array will make a copy of the item and will not take
ownership of the original item. Once again, it only makes sense for wxObjArrays
because the other array types never take ownership of their elements. Also note
that you cannot append more than one pointer as reusing it would lead to
deleting it twice (or more) and hence to a crash.

You may also use \helpref{WX\_APPEND\_ARRAY}{wxappendarray} macro to append all
elements of one array to another one but it is more efficient to use
{\it copies} parameter and modify the elements in place later if you plan to
append a lot of items.

\membersection{wxArray::Alloc}\label{wxarrayalloc}

\func{void}{Alloc}{\param{size\_t }{count}}

Preallocates memory for a given number of array elements. It is worth calling
when the number of items which are going to be added to the array is known in
advance because it will save unneeded memory reallocation. If the array already
has enough memory for the given number of items, nothing happens. In any case,
the existing contents of the array is not modified.

\membersection{wxArray::Clear}\label{wxarrayclear}

\func{void}{Clear}{\void}

This function does the same as \helpref{Empty()}{wxarrayempty} and additionally
frees the memory allocated to the array.

\membersection{wxArray::Count}\label{wxarraycount}

\constfunc{size\_t}{Count}{\void}

Same as \helpref{GetCount()}{wxarraygetcount}. This function is deprecated -
it exists only for compatibility.

\membersection{wxObjArray::Detach}\label{wxobjarraydetach}

\func{T *}{Detach}{\param{size\_t }{index}}

Removes the element from the array, but, unlike,
\helpref{Remove()}{wxarrayremove} doesn't delete it. The function returns the
pointer to the removed element.

\membersection{wxArray::Empty}\label{wxarrayempty}

\func{void}{Empty}{\void}

Empties the array. For wxObjArray classes, this destroys all of the array
elements. For wxArray and wxSortedArray this does nothing except marking the
array of being empty - this function does not free the allocated memory, use
\helpref{Clear()}{wxarrayclear} for this.

\membersection{wxArray::GetCount}\label{wxarraygetcount}

\constfunc{size\_t}{GetCount}{\void}

Return the number of items in the array.

\membersection{wxArray::Index}\label{wxarrayindex}

\constfunc{int}{Index}{\param{T\& }{item}, \param{bool }{searchFromEnd = false}}

\constfunc{int}{Index}{\param{T\& }{item}}

The first version of the function is for wxArray and wxObjArray, the second is
for wxSortedArray only.

Searches the element in the array, starting from either beginning or the end
depending on the value of {\it searchFromEnd} parameter. {\tt wxNOT\_FOUND} is
returned if the element is not found, otherwise the index of the element is
returned.

Linear search is used for the wxArray and wxObjArray classes but binary search
in the sorted array is used for wxSortedArray (this is why searchFromEnd
parameter doesn't make sense for it).

{\bf NB:} even for wxObjArray classes, the operator==() of the elements in the
array is {\bf not} used by this function. It searches exactly the given
element in the array and so will only succeed if this element had been
previously added to the array, but fail even if another, identical, element is
in the array.

\membersection{wxArray::Insert}\label{wxarrayinsert}

\func{void}{Insert}{\param{T }{item}, \param{size\_t }{n}, \param{size\_t }{copies = $1$}}

\func{void}{Insert}{\param{T *}{item}, \param{size\_t }{n}}

\func{void}{Insert}{\param{T \&}{item}, \param{size\_t }{n}, \param{size\_t }{copies = $1$}}

Insert the given number of {\it copies} of the {\it item} into the array before
the existing item {\it n} - thus, {\it Insert(something, 0u)} will insert an
item in such way that it will become the first array element.

Please see \helpref{Add()}{wxarrayadd} for explanation of the differences
between the overloaded versions of this function.

\membersection{wxArray::IsEmpty}\label{wxarrayisempty}

\constfunc{bool}{IsEmpty}{\void}

Returns true if the array is empty, false otherwise.

\membersection{wxArray::Item}\label{wxarrayitem}

\constfunc{T\&}{Item}{\param{size\_t }{index}}

Returns the item at the given position in the array. If {\it index} is out of
bounds, an assert failure is raised in the debug builds but nothing special is
done in the release build.

The returned value is of type "reference to the array element type" for all of
the array classes.

\membersection{wxArray::Last}\label{wxarraylast}

\constfunc{T\&}{Last}{\void}

Returns the last element in the array, i.e. is the same as Item(GetCount() - 1).
An assert failure is raised in the debug mode if the array is empty.

The returned value is of type "reference to the array element type" for all of
the array classes.

\membersection{wxArray::Remove}\label{wxarrayremove}

\func{\void}{Remove}{\param{T }{item}}

Removes an element from the array by value: the first item of the
array equal to {\it item} is removed, an assert failure will result from an
attempt to remove an item which doesn't exist in the array.

When an element is removed from wxObjArray it is deleted by the array - use
\helpref{Detach()}{wxobjarraydetach} if you don't want this to happen. On the
other hand, when an object is removed from a wxArray nothing happens - you
should delete it manually if required:

\begin{verbatim}
T *item = array[n];
delete item;
array.Remove(n)
\end{verbatim}

See also \helpref{WX\_CLEAR\_ARRAY}{wxcleararray} macro which deletes all
elements of a wxArray (supposed to contain pointers).

\membersection{wxArray::RemoveAt}\label{wxarrayremoveat}

\func{\void}{RemoveAt}{\param{size\_t }{index}, \param{size\_t }{count = $1$}}

Removes {\it count} elements starting at {\it index} from the array. When an
element is removed from wxObjArray it is deleted by the array - use
\helpref{Detach()}{wxobjarraydetach} if you don't want this to happen. On
the other hand, when an object is removed from a wxArray nothing happens -
you should delete it manually if required:

\begin{verbatim}
T *item = array[n];
delete item;
array.RemoveAt(n)
\end{verbatim}

See also \helpref{WX\_CLEAR\_ARRAY}{wxcleararray} macro which deletes all
elements of a wxArray (supposed to contain pointers).

\membersection{wxArray::SetCount}\label{wxarraysetcount}

\func{void}{SetCount}{\param{size\_t }{count}, \param{T }{defval = T($0$)}}

This function ensures that the number of array elements is at least
{\it count}. If the array has already {\it count} or more items, nothing is
done. Otherwise, {\tt count - GetCount()} elements are added and initialized to
the value {\it defval}.

\wxheading{See also}

\helpref{GetCount}{wxarraygetcount}

\membersection{wxArray::Shrink}\label{wxarrayshrink}

\func{void}{Shrink}{\void}

Frees all memory unused by the array. If the program knows that no new items
will be added to the array it may call Shrink() to reduce its memory usage.
However, if a new item is added to the array, some extra memory will be
allocated again.

\membersection{wxArray::Sort}\label{wxarraysort}

\func{void}{Sort}{\param{CMPFUNC<T> }{compareFunction}}

The notation CMPFUNC<T> should be read as if we had the following declaration:

\begin{verbatim}
template int CMPFUNC(T *first, T *second);
\end{verbatim}

where {\it T} is the type of the array elements. I.e. it is a function returning
{\it int} which is passed two arguments of type {\it T *}.

Sorts the array using the specified compare function: this function should
return a negative, zero or positive value according to whether the first element
passed to it is less than, equal to or greater than the second one.

wxSortedArray doesn't have this function because it is always sorted.