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/*!

    \class QVarLengthArray

    \brief The QVarLengthArray class provides a low-level variable-length array.

    \ingroup tools

    \reentrant

    The C++ language doesn't support variable-length arrays on the stack.

    For example, the following code won't compile:

    \snippet doc/src/snippets/code/doc_src_qvarlengtharray.qdoc 0

    The alternative is to allocate the array on the heap (with

    \c{new}):

    \snippet doc/src/snippets/code/doc_src_qvarlengtharray.qdoc 1

    However, if myfunc() is called very frequently from the

    application's inner loop, heap allocation can be a major source

    of slowdown.

    QVarLengthArray is an attempt to work around this gap in the C++

    language. It allocates a certain number of elements on the stack,

    and if you resize the array to a larger size, it automatically

    uses the heap instead. Stack allocation has the advantage that

    it is much faster than heap allocation.

    Example:

    \snippet doc/src/snippets/code/doc_src_qvarlengtharray.qdoc 2

    In the example above, QVarLengthArray will preallocate 1024

    elements on the stack and use them unless \c{n + 1} is greater

    than 1024. If you omit the second template argument,

    QVarLengthArray's default of 256 is used.

    QVarLengthArray's value type must be an \l{assignable data type}.

    This covers most data types that are commonly used, but the

    compiler won't let you, for example, store a QWidget as a value;

    instead, store a QWidget *.

    QVarLengthArray, like QVector, provides a resizable array data

    structure. The main differences between the two classes are:

    \list

    \o QVarLengthArray's API is much more low-level. It provides no

       iterators and lacks much of QVector's functionality.

    \o QVarLengthArray doesn't initialize the memory if the value is

       a basic type. (QVector always does.)

    \o QVector uses \l{implicit sharing} as a memory optimization.

       QVarLengthArray doesn't provide that feature; however, it

       usually produces slightly better performance due to reduced

       overhead, especially in tight loops.

    \endlist

    In summary, QVarLengthArray is a low-level optimization class

    that only makes sense in very specific cases. It is used a few

    places inside Qt and was added to Qt's public API for the

    convenience of advanced users.

    \sa QVector, QList, QLinkedList

*/

/*! \fn QVarLengthArray::QVarLengthArray(int size)

    Constructs an array with an initial size of \a size elements.

    If the value type is a primitive type (e.g., char, int, float) or

    a pointer type (e.g., QWidget *), the elements are not

    initialized. For other types, the elements are initialized with a

    \l{default-constructed value}.

*/

/*! \fn QVarLengthArray::~QVarLengthArray()

    Destroys the array.

*/

/*! \fn int QVarLengthArray::size() const

    Returns the number of elements in the array.

    \sa isEmpty(), resize()

*/

/*! \fn int QVarLengthArray::count() const

    Same as size().

    \sa isEmpty(), resize()

*/

/*! \fn bool QVarLengthArray::isEmpty() const

    Returns true if the array has size 0; otherwise returns false.

    \sa size(), resize()

*/

/*! \fn void QVarLengthArray::clear()

    Removes all the elements from the array.

    Same as resize(0).

*/

/*! \fn void QVarLengthArray::resize(int size)

    Sets the size of the array to \a size. If \a size is greater than

    the current size, elements are added to the end. If \a size is

    less than the current size, elements are removed from the end.

    If the value type is a primitive type (e.g., char, int, float) or

    a pointer type (e.g., QWidget *), new elements are not

    initialized. For other types, the elements are initialized with a

    \l{default-constructed value}.

    \sa size()

*/

/*! \fn int QVarLengthArray::capacity() const

    Returns the maximum number of elements that can be stored in the

    array without forcing a reallocation.

    The sole purpose of this function is to provide a means of fine

    tuning QVarLengthArray's memory usage. In general, you will rarely ever

    need to call this function. If you want to know how many items are

    in the array, call size().

    \sa reserve()

*/

/*! \fn void QVarLengthArray::reserve(int size)

    Attempts to allocate memory for at least \a size elements. If you

    know in advance how large the array can get, you can call this

    function and if you call resize() often, you are likely to get

    better performance. If \a size is an underestimate, the worst

    that will happen is that the QVarLengthArray will be a bit

    slower.

    The sole purpose of this function is to provide a means of fine

    tuning QVarLengthArray's memory usage. In general, you will

    rarely ever need to call this function. If you want to change the

    size of the array, call resize().

    \sa capacity()

*/

/*! \fn T &QVarLengthArray::operator[](int i)

    Returns a reference to the item at index position \a i.

    \a i must be a valid index position in the array (i.e., 0 <= \a i

    < size()).

    \sa data(), at()

*/

/*! \fn const T &QVarLengthArray::operator[](int i) const

    \overload

*/

/*!

    \fn void QVarLengthArray::append(const T &t)

    Appends item \a t to the array, extending the array if necessary.

    \sa removeLast()

*/

/*!

    \fn inline void QVarLengthArray::removeLast()

    \since 4.5

    Decreases the size of the array by one.  The allocated size is not changed.

    \sa append()

*/

/*!

    \fn void QVarLengthArray::append(const T *buf, int size)

    Appends \a size amount of items referenced by \a buf to this array.

*/

/*! \fn T *QVarLengthArray::data()

    Returns a pointer to the data stored in the array. The pointer can

    be used to access and modify the items in the array.

    Example:

    \snippet doc/src/snippets/code/doc_src_qvarlengtharray.qdoc 3

    The pointer remains valid as long as the array isn't reallocated.

    This function is mostly useful to pass an array to a function

    that accepts a plain C++ array.

    \sa constData(), operator[]()

*/

/*! \fn const T *QVarLengthArray::data() const

    \overload

*/

/*! \fn const T *QVarLengthArray::constData() const

    Returns a const pointer to the data stored in the array. The

    pointer can be used to access the items in the array. The

    pointer remains valid as long as the array isn't reallocated.

    This function is mostly useful to pass an array to a function

    that accepts a plain C++ array.

    \sa data(), operator[]()

*/

/*! \fn QVarLengthArray<T, Prealloc> &QVarLengthArray::operator=(const QVarLengthArray<T, Prealloc> &other)

    Assigns \a other to this array and returns a reference to this array.

 */

/*! \fn QVarLengthArray::QVarLengthArray(const QVarLengthArray<T, Prealloc> &other)

    Constructs a copy of \a other.

 */

/*! \fn const T &QVarLengthArray::at(int i) const

    Returns a reference to the item at index position \a i.

    \a i must be a valid index position in the array (i.e., 0 <= \a i

    < size()).

    \sa value(), operator[]()

*/

/*! \fn T QVarLengthArray::value(int i) const

    Returns the value at index position \a i.

    If the index \a i is out of bounds, the function returns

    a \l{default-constructed value}. If you are certain that

    \a i is within bounds, you can use at() instead, which is slightly

    faster.

    \sa at(), operator[]()

*/

/*! \fn T QVarLengthArray::value(int i, const T &defaultValue) const

    \overload

    If the index \a i is out of bounds, the function returns

    \a defaultValue.

*/

/*!

    \typedef QVarLengthArray::size_type

    \since 4.7

    Typedef for int. Provided for STL compatibility.

*/

/*!

    \typedef QVarLengthArray::value_type

    \since 4.7

    Typedef for T. Provided for STL compatibility.

*/

/*!

    \typedef QVarLengthArray::difference_type

    \since 4.7

    Typedef for ptrdiff_t. Provided for STL compatibility.

*/

/*!

    \typedef QVarLengthArray::pointer

    \since 4.7

    Typedef for T *. Provided for STL compatibility.

*/

/*!

    \typedef QVarLengthArray::const_pointer

    \since 4.7

    Typedef for const T *. Provided for STL compatibility.

*/

/*!

    \typedef QVarLengthArray::reference

    \since 4.7

    Typedef for T &. Provided for STL compatibility.

*/

/*!

    \typedef QVarLengthArray::const_reference

    \since 4.7

    Typedef for const T &. Provided for STL compatibility.

*/