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QMemArray(3qt)							QMemArray(3qt)

NAME
       QMemArray - Template class that provides arrays of simple types

SYNOPSIS
       All the functions in this class are reentrant when Qt is built with
       thread support.</p>

       #include <qmemarray.h>

       Inherited by QByteArray and QPointArray.

   Public Members
       typedef type * Iterator
       typedef const type * ConstIterator
       QMemArray ()
       QMemArray ( int size )
       QMemArray ( const QMemArray<type> & a )
       ~QMemArray ()
       QMemArray<type> & operator= ( const QMemArray<type> & a )
       type * data () const
       uint nrefs () const
       uint size () const
       uint count () const
       bool isEmpty () const
       bool isNull () const
       bool resize ( uint size )
       bool resize ( uint size, Optimization optim )
       bool truncate ( uint pos )
       bool fill ( const type & v, int size = -1 )
       virtual void detach ()
       QMemArray<type> copy () const
       QMemArray<type> & assign ( const QMemArray<type> & a )
       QMemArray<type> & assign ( const type * data, uint size )
       QMemArray<type> & duplicate ( const QMemArray<type> & a )
       QMemArray<type> & duplicate ( const type * data, uint size )
       QMemArray<type> & setRawData ( const type * data, uint size )
       void resetRawData ( const type * data, uint size )
       int find ( const type & v, uint index = 0 ) const
       int contains ( const type & v ) const
       void sort ()
       int bsearch ( const type & v ) const
       type & operator[] ( int index ) const
       type & at ( uint index ) const
       operator const type * () const
       bool operator== ( const QMemArray<type> & a ) const
       bool operator!= ( const QMemArray<type> & a ) const
       Iterator begin ()
       Iterator end ()
       ConstIterator begin () const
       ConstIterator end () const

   Protected Members
       QMemArray ( int, int )

RELATED FUNCTION DOCUMENTATION
       Q_UINT16 qChecksum ( const char * data, uint len )
       QDataStream & operator<< ( QDataStream & s, const QByteArray & a )
       QDataStream & operator>> ( QDataStream & s, QByteArray & a )

DESCRIPTION
       The QMemArray class is a template class that provides arrays of simple
       types.

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

       QMemArray 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). QMemArray uses
       bitwise operations to copy and compare array elements.

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

       QMemArray 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.

       An alternative to QMemArray is QValueVector. The QValueVector class
       also provides an array of objects, but can deal with objects that have
       constructors (specifically a copy constructor and a default
       constructor). QValueVector provides an STL-compatible syntax and is
       implicitly shared.

       Example:

	   #include <qmemarray.h>
	   #include <stdio.h>
	   QMemArray<int> fib( int num ) // returns fibonacci array
	   {
	       Q_ASSERT( num > 2 );
	       QMemArray<int> f( num ); // array of ints
	       f[0] = f[1] = 1;
	       for ( int i = 2; i < num; i++ )
		   f[i] = f[i-1] + f[i-2];
	       return f;
	   }
	   int main()
	   {
	       QMemArray<int> a = fib( 6 ); // get first 6 fibonaccis
	       for ( int i = 0; i < a.size(); i++ )
		   qDebug( "%d: %d", i, a[i] );
	       qDebug( "1 is found %d times", a.contains(1) );
	       qDebug( "5 is found at index %d", a.find(5) );
	       return 0;
	   }

       Program output:

	   0: 1
	   1: 1
	   2: 2
	   3: 3
	   4: 5
	   5: 8
	   1 is found 2 times
	   5 is found at index 4

       Note concerning the use of QMemArray 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 QMemArray 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:

	   // MyStruct may be padded to 4 or 8 bytes
	   struct MyStruct
	   {
	       short i; // 2 bytes
	       char c;	// 1 byte
	   };
	   QMemArray<MyStruct> a(1);
	   a[0].i = 5;
	   a[0].c = 't';
	   MyStruct x;
	   x.i = '5';
	   x.c = 't';
	   int i = a.find( x ); // may return -1 if the pad bytes differ

       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.

       QMemArray 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.

       See also Shared Classes and Non-GUI Classes.

   Member Type Documentation
QMemArray::ConstIterator
       A const QMemArray iterator.

       See also begin() and end().

QMemArray::Iterator
       A QMemArray iterator.

       See also begin() and end().

MEMBER FUNCTION DOCUMENTATION
QMemArray::QMemArray ( int, int ) [protected]
       Constructs an array without allocating array space. The arguments
       should be (0, 0). Use at your own risk.

QMemArray::QMemArray ()
       Constructs a null array.

       See also isNull().

QMemArray::QMemArray ( int size )
       Constructs an array with room for size elements. Makes a null array if
       size == 0.

       The elements are left uninitialized.

       See also resize() and isNull().

QMemArray::QMemArray ( const QMemArray<;type> & a )
       Constructs a shallow copy of a.

       See also assign().

QMemArray::~QMemArray ()
       Dereferences the array data and deletes it if this was the last
       reference.

QMemArray<;type> & QMemArray::assign ( const QMemArray<type> & a )
       Shallow copy. Dereferences the current array and references the data
       contained in a instead. Returns a reference to this array.

       See also operator=().

QMemArray<;type> & QMemArray::assign ( const type * data, uint size )
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Shallow copy. Dereferences the current array and references the array
       data data, which contains size elements. Returns a reference to this
       array.

       Do not delete data later; QMemArray will call free() on it at the right
       time.

type & QMemArray::at ( uint index ) const
       Returns a reference to the element at position index in the array.

       This can be used to both read and set an element.

       See also operator[]().

Iterator QMemArray::begin ()
       Returns an iterator pointing at the beginning of this array. This
       iterator can be used in the same way as the iterators of QValueList and
       QMap, for example.

ConstIterator QMemArray::begin () const
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Returns a const iterator pointing at the beginning of this array. This
       iterator can be used in the same way as the iterators of QValueList and
       QMap, for example.

int QMemArray::bsearch ( const type & v ) const
       In a sorted array (as sorted by sort()), finds the first occurrence of
       v by using a binary search. For a sorted array this is generally much
       faster than find(), which does a linear search.

       Returns the position of v, or -1 if v could not be found.

       See also sort() and find().

int QMemArray::contains ( const type & v ) const
       Returns the number of times v occurs in the array.

       See also find().

QMemArray<;type> QMemArray::copy () const
       Returns a deep copy of this array.

       See also detach() and duplicate().

uint QMemArray::count () const
       Returns the same as size().

       See also size().

       Example: scribble/scribble.cpp.

type * QMemArray::data () const
       Returns a pointer to the actual array data.

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

       See also isNull().

       Examples:

void QMemArray::detach () [virtual]
       Detaches this array from shared array data; i.e. it makes a private,
       deep copy of the data.

       Copying will be performed only if the reference count is greater than
       one.

       See also copy().

       Reimplemented in QBitArray.

QMemArray<;type> & QMemArray::duplicate ( const QMemArray<type> & a )
       Deep copy. Dereferences the current array and obtains a copy of the
       data contained in a instead. Returns a reference to this array.

       See also copy().

QMemArray<;type> & QMemArray::duplicate ( const type * data, uint size )
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Deep copy. Dereferences the current array and obtains a copy of the
       array data data instead. Returns a reference to this array. The size of
       the array is given by size.

       See also copy().

Iterator QMemArray::end ()
       Returns an iterator pointing behind the last element of this array.
       This iterator can be used in the same way as the iterators of
       QValueList and QMap, for example.

ConstIterator QMemArray::end () const
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Returns a const iterator pointing behind the last element of this
       array. This iterator can be used in the same way as the iterators of
       QValueList and QMap, for example.

bool QMemArray::fill ( const type & v, int size = -1 )
       Fills the array with the value v. If size is specified as different
       from -1, then the array will be resized before being filled.

       Returns TRUE if successful, i.e. if size is -1, or size is != -1 and
       the memory can be allocated; otherwise returns FALSE.

       See also resize().

int QMemArray::find ( const type & v, uint index = 0 ) const
       Finds the first occurrence of v, starting at position index.

       Returns the position of v, or -1 if v could not be found.

       See also contains().

bool QMemArray::isEmpty () const
       Returns TRUE if the array is empty; otherwise returns FALSE.

       isEmpty() is equivalent to isNull() for QMemArray (unlike QString).

bool QMemArray::isNull () const
       Returns TRUE if the array is null; otherwise returns FALSE.

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

uint QMemArray::nrefs () const
       Returns the reference count for the shared array data. This reference
       count is always greater than zero.

QMemArray::operator const type * () const
       Cast operator. Returns a pointer to the array.

       See also data().

bool QMemArray::operator!= ( const QMemArray<type> & a ) const
       Returns TRUE if this array is different from a; otherwise returns
       FALSE.

       The two arrays are compared bitwise.

       See also operator==().

QMemArray<;type> & QMemArray::operator= ( const QMemArray<type> & a )
       Assigns a shallow copy of a to this array and returns a reference to
       this array.

       Equivalent to assign( a ).

bool QMemArray::operator== ( const QMemArray<type> & a ) const
       Returns TRUE if this array is equal to a; otherwise returns FALSE.

       The two arrays are compared bitwise.

       See also operator!=().

type & QMemArray::operator[] ( int index ) const
       Returns a reference to the element at position index in the array.

       This can be used to both read and set an element. Equivalent to at().

       See also at().

void QMemArray::resetRawData ( const type * data, uint size )
       Removes internal references to the raw data that was set using
       setRawData(). This means that QMemArray no longer has access to the
       data, so you are free to manipulate data as you wish. You can now use
       the QMemArray without affecting the original data, for example by
       calling setRawData() with a pointer to some other data.

       The arguments must be the data and length, size, that were passed to
       setRawData(). This is for consistency checking.

       See also setRawData().

bool QMemArray::resize ( uint size, Optimization optim )
       Resizes (expands or shrinks) the array to size elements. The array
       becomes a null array if size == 0.

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

       New elements are not initialized.

       optim is either QGArray::MemOptim (the default) or QGArray::SpeedOptim.

       Note: By default, SpeedOptim is not available for general use since it
       is only available if Qt is built in a particular configuration.

       See also size().

       Example: fileiconview/qfileiconview.cpp.

bool QMemArray::resize ( uint size )
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

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

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

       New elements are not initialized.

       See also size().

QMemArray<;type> & QMemArray::setRawData ( const type * data, uint size )
       Sets raw data and returns a reference to the array.

       Dereferences the current array and sets the new array data to data and
       the new array size to size. Do not attempt to resize or re-assign the
       array data when raw data has been set. Call resetRawData(data, size) to
       reset the array.

       Setting raw data is useful because it sets QMemArray data without
       allocating memory or copying data.

       Example I (intended use):

	   static char bindata[] = { 231, 1, 44, ... };
	   QByteArray  a;
	   a.setRawData( bindata, sizeof(bindata) );   // a points to bindata
	   QDataStream s( a, IO_ReadOnly );	       // open on a's data
	   s >> <something>;			       // read raw bindata
	   a.resetRawData( bindata, sizeof(bindata) ); // finished

       Example II (you don't want to do this):

	   static char bindata[] = { 231, 1, 44, ... };
	   QByteArray  a, b;
	   a.setRawData( bindata, sizeof(bindata) );   // a points to bindata
	   a.resize( 8 );			       // will crash
	   b = a;				       // will crash
	   a[2] = 123;				       // might crash
	   // forget to resetRawData: will crash

       Warning: If you do not call resetRawData(), QMemArray will attempt to
       deallocate or reallocate the raw data, which might not be too good. Be
       careful.

       See also resetRawData().

uint QMemArray::size () const
       Returns the size of the array (maximum number of elements).

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

       See also isNull() and resize().

void QMemArray::sort ()
       Sorts the array elements in ascending order, using bitwise comparison
       (memcmp()).

       See also bsearch().

bool QMemArray::truncate ( uint pos )
       Truncates the array at position pos.

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

       Equivalent to resize(pos).

       See also resize().

RELATED FUNCTION DOCUMENTATION
QDataStream & operator<;< ( QDataStream & s, const QByteArray & a )
       Writes byte array a to the stream s and returns a reference to the
       stream.

       See also Format of the QDataStream operators.

QDataStream & operator>> ( QDataStream & s, QByteArray & a )
       Reads a byte array into a from the stream s and returns a reference to
       the stream.

       See also Format of the QDataStream operators.

Q_UINT16 qChecksum ( const char * data, uint len )
       Returns the CRC-16 checksum of len bytes starting at data.

       The checksum is independent of the byte order (endianness).

SEE ALSO
       http://doc.trolltech.com/qmemarray.html
       http://www.trolltech.com/faq/tech.html

COPYRIGHT
       Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com.  See the
       license file included in the distribution for a complete license
       statement.

AUTHOR
       Generated automatically from the source code.

BUGS
       If you find a bug in Qt, please report it as described in
       http://doc.trolltech.com/bughowto.html.	Good bug reports help us to
       help you. Thank you.

       The definitive Qt documentation is provided in HTML format; it is
       located at $QTDIR/doc/html and can be read using Qt Assistant or with a
       web browser. This man page is provided as a convenience for those users
       who prefer man pages, although this format is not officially supported
       by Trolltech.

       If you find errors in this manual page, please report them to qt-
       bugs@trolltech.com.  Please include the name of the manual page
       (qmemarray.3qt) and the Qt version (3.3.8).

Trolltech AS			2 February 2007			QMemArray(3qt)
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