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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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