source: trunk/src/qt3support/tools/q3memarray.qdoc@ 792

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/*!
    \class Q3MemArray
    \brief The Q3MemArray class is a template class that provides arrays of simple types.
    \compat

    Q3MemArray is implemented as a template class. Define a template
    instance Q3MemArray\<X\> to create an array that contains X items.

    Q3MemArray stores the array elements directly in the array. It can
    only deal with simple types (i.e. C++ types, structs, and classes
    that have no constructors, destructors, or virtual functions).
    Q3MemArray uses bitwise operations to copy and compare array
    elements. 

    The Q3PtrVector collection class is also a kind of array. Like most
    old Qt collection classes, it uses pointers to the contained items.

    Q3MemArray uses explicit sharing with a
    reference count. If more than one array shares common data and one
    of the arrays is modified, all the arrays are modified.

    The benefit of sharing is that a program does not need to duplicate
    data when it is not required, which results in lower memory use
    and less copying of data.

    Example:
    \snippet doc/src/snippets/code/doc_src_q3memarray.qdoc 0

    Program output:
    \snippet doc/src/snippets/code/doc_src_q3memarray.qdoc 1

    Note concerning the use of Q3MemArray for manipulating structs or
    classes: Compilers will often pad the size of structs of odd sizes
    up to the nearest word boundary. This will then be the size
    Q3MemArray will use for its bitwise element comparisons. Because
    the remaining bytes will typically be uninitialized, this can
    cause find() etc. to fail to find the element. Example:

    \snippet doc/src/snippets/code/doc_src_q3memarray.qdoc 2

    To work around this, make sure that you use a struct where
    sizeof() returns the same as the sum of the sizes of the members
    either by changing the types of the struct members or by adding
    dummy members.

    Q3MemArray data can be traversed by iterators (see begin() and
    end()). The number of items is returned by count(). The array can
    be resized with resize() and filled using fill().

    You can make a shallow copy of the array with assign() (or
    operator=()) and a deep copy with duplicate().

    Search for values in the array with find() and contains(). For
    sorted arrays (see sort()) you can search using bsearch().

    You can set the data directly using setRawData() and
    resetRawData(), although this requires care.
*/

/*! \fn Q3MemArray::operator QVector<type>() const

    Automatically converts the Q3MemArray<type> into a QVector<type>.
*/

/*! \typedef Q3MemArray::Iterator
    A Q3MemArray iterator.
    \sa begin() end()
*/
/*! \typedef Q3MemArray::ConstIterator
    A const Q3MemArray iterator.
    \sa begin() end()
*/
/*! \typedef Q3MemArray::ValueType
    \internal
*/

/*!
    \fn Q3MemArray::Q3MemArray()

    Constructs a null array.

    \sa isNull()
*/

/*!
    \fn Q3MemArray::Q3MemArray( int size )

    Constructs an array with room for \a size elements. Makes a null
    array if \a size == 0.

    The elements are left uninitialized.

    \sa resize(), isNull()
*/

/*!
    \fn Q3MemArray::Q3MemArray( const Q3MemArray<type> &a )

    Constructs a shallow copy of \a a.

    \sa assign()
*/

/*!
    \fn Q3MemArray::Q3MemArray(const QVector<type> &vector)

    Constructs a copy of \a vector.
*/

/*!
    \fn Q3MemArray::Q3MemArray(int arg1, int arg2)

    Constructs an array \e{without allocating} array space. The
    arguments \a arg1 and \a arg2 should be zero. Use at your own
    risk.
*/

/*!
    \fn Q3MemArray::~Q3MemArray()

    Dereferences the array data and deletes it if this was the last
    reference.
*/

/*!
    \fn Q3MemArray<type> &Q3MemArray::operator=( const Q3MemArray<type> &a )

    Assigns a shallow copy of \a a to this array and returns a
    reference to this array.

    Equivalent to assign( a ).
*/

/*!
    \fn type *Q3MemArray::data() const

    Returns a pointer to the actual array data.

    The array is a null array if data() == 0 (null pointer).

    \sa isNull()
*/

/*!
    \fn uint Q3MemArray::nrefs() const

    Returns the reference count for the shared array data. This
    reference count is always greater than zero.
*/

/*!
    \fn uint Q3MemArray::size() const

    Returns the size of the array (maximum number of elements).

    The array is a null array if size() == 0.

    \sa isNull(), resize()
*/

/*!
    \fn uint Q3MemArray::count() const

    Returns the same as size().

    \sa size()
*/

/*!
    \fn bool Q3MemArray::isEmpty() const

    Returns TRUE if the array is empty; otherwise returns FALSE.

    isEmpty() is equivalent to isNull() for Q3MemArray (unlike
    QString).
*/

/*!
    \fn bool Q3MemArray::isNull() const

    Returns TRUE if the array is null; otherwise returns FALSE.

    A null array has size() == 0 and data() == 0.
*/

/*!
    \fn bool Q3MemArray::resize( uint size, Optimization optim )

    Resizes (expands or shrinks) the array to \a size elements. The
    array becomes a null array if \a size == 0.

    Returns TRUE if successful, or FALSE if the memory cannot be
    allocated.

    New elements are not initialized.

    \a optim is either Q3GArray::MemOptim (the default) or
    Q3GArray::SpeedOptim. When optimizing for speed rather than memory
    consumption, the array uses a smart grow and shrink algorithm that
    might allocate more memory than is actually needed for \a size
    elements. This speeds up subsequent resize operations, for example
    when appending many elements to an array, since the space has
    already been allocated.

    \sa size()
*/

/*!
    \fn bool Q3MemArray::resize( uint size )

    \overload

    Resizes (expands or shrinks) the array to \a size elements. The
    array becomes a null array if \a size == 0.

    Returns TRUE if successful, i.e. if the memory can be allocated;
    otherwise returns FALSE.

    New elements are not initialized.

    \sa size()
*/

/*!
    \fn bool Q3MemArray::truncate( uint pos )

    Truncates the array at position \a pos.

    Returns TRUE if successful, i.e. if the memory can be allocated;
    otherwise returns FALSE.

    Equivalent to resize(\a pos).