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235 lines
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235 lines
10 KiB
14 years ago
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<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/qptrlist.doc:840 -->
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<title>QPtrListIterator Class</title>
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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QPtrListIterator Class Reference</h1>
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<p>The QPtrListIterator class provides an iterator for
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QPtrList collections.
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<a href="#details">More...</a>
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<p><tt>#include <<a href="qptrlist-h.html">qptrlist.h</a>></tt>
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<p>Inherited by <a href="qobjectlistiterator.html">QObjectListIterator</a> and <a href="qstrlistiterator.html">QStrListIterator</a>.
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<p><a href="qptrlistiterator-members.html">List of all member functions.</a>
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<h2>Public Members</h2>
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<ul>
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<li class=fn><a href="#QPtrListIterator"><b>QPtrListIterator</b></a> ( const QPtrList<type> & list )</li>
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<li class=fn><a href="#~QPtrListIterator"><b>~QPtrListIterator</b></a> ()</li>
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<li class=fn>uint <a href="#count"><b>count</b></a> () const</li>
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<li class=fn>bool <a href="#isEmpty"><b>isEmpty</b></a> () const</li>
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<li class=fn>bool <a href="#atFirst"><b>atFirst</b></a> () const</li>
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<li class=fn>bool <a href="#atLast"><b>atLast</b></a> () const</li>
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<li class=fn>type * <a href="#toFirst"><b>toFirst</b></a> ()</li>
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<li class=fn>type * <a href="#toLast"><b>toLast</b></a> ()</li>
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<li class=fn><a href="#operator-type-*"><b>operator type *</b></a> () const</li>
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<li class=fn>type * <a href="#operator*"><b>operator*</b></a> ()</li>
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<li class=fn>type * <a href="#current"><b>current</b></a> () const</li>
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<li class=fn>type * <a href="#operator()"><b>operator()</b></a> ()</li>
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<li class=fn>type * <a href="#operator++"><b>operator++</b></a> ()</li>
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<li class=fn>type * <a href="#operator+-eq"><b>operator+=</b></a> ( uint jump )</li>
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<li class=fn>type * <a href="#operator--"><b>operator--</b></a> ()</li>
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<li class=fn>type * <a href="#operator--eq"><b>operator-=</b></a> ( uint jump )</li>
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<li class=fn>QPtrListIterator<type> & <a href="#operator-eq"><b>operator=</b></a> ( const QPtrListIterator<type> & it )</li>
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</ul>
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<hr><a name="details"></a><h2>Detailed Description</h2>
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The QPtrListIterator class provides an iterator for
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<a href="qptrlist.html">QPtrList</a> collections.
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<p>
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<p> Define a template instance QPtrListIterator<X> to create a list
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iterator that operates on QPtrList<X> (list of X*).
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<p> The following example is similar to the <a href="qptrlist.html#example">example in the QPtrList class documentation</a>, but it uses QPtrListIterator. The class Employee is
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defined there.
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<p> <pre>
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<a href="qptrlist.html">QPtrList</a><Employee> list;
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list.<a href="qptrlist.html#append">append</a>( new Employee("John", "Doe", 50000) );
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list.<a href="qptrlist.html#append">append</a>( new Employee("Jane", "Williams", 80000) );
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list.<a href="qptrlist.html#append">append</a>( new Employee("Tom", "Jones", 60000) );
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QPtrListIterator<Employee> it( list );
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Employee *employee;
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while ( (employee = it.<a href="#current">current</a>()) != 0 ) {
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++it;
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cout << employee->surname().latin1() << ", " <<
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employee->forename().latin1() << " earns " <<
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employee->salary() << endl;
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}
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</pre>
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<p> The output is
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<pre>
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Doe, John earns 50000
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Williams, Jane earns 80000
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Jones, Tom earns 60000
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</pre>
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<p> Using a list iterator is a more robust way of traversing the list
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than using the <a href="qptrlist.html">QPtrList</a> member functions <a href="qptrlist.html#first">first</a>(), <a href="qptrlist.html#next">next</a>(), <a href="qptrlist.html#current">current</a>(), etc., as many iterators can
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traverse the same list independently.
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<p> An iterator has its own current list item and can get the next and
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previous list items. It doesn't modify the list in any way.
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<p> When an item is removed from the list, all iterators that point to
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that item are updated to point to <a href="qptrlist.html#current">QPtrList::current</a>() instead to
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avoid dangling references.
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<p> <p>See also <a href="qptrlist.html">QPtrList</a>, <a href="collection.html">Collection Classes</a>, and <a href="tools.html">Non-GUI Classes</a>.
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<hr><h2>Member Function Documentation</h2>
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<h3 class=fn><a name="QPtrListIterator"></a>QPtrListIterator::QPtrListIterator ( const <a href="qptrlist.html">QPtrList</a><type> & list )
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</h3>
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<p> Constructs an iterator for <em>list</em>. The current iterator item is
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set to point on the first item in the <em>list</em>.
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<h3 class=fn><a name="~QPtrListIterator"></a>QPtrListIterator::~QPtrListIterator ()
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</h3>
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<p> Destroys the iterator.
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<h3 class=fn>bool <a name="atFirst"></a>QPtrListIterator::atFirst () const
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</h3>
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<p> Returns TRUE if the current iterator item is the first list item;
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otherwise returns FALSE.
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<p> <p>See also <a href="#toFirst">toFirst</a>() and <a href="#atLast">atLast</a>().
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<h3 class=fn>bool <a name="atLast"></a>QPtrListIterator::atLast () const
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</h3>
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<p> Returns TRUE if the current iterator item is the last list item;
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otherwise returns FALSE.
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<p> <p>See also <a href="#toLast">toLast</a>() and <a href="#atFirst">atFirst</a>().
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<h3 class=fn>uint <a name="count"></a>QPtrListIterator::count () const
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</h3>
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<p> Returns the number of items in the list this iterator operates on.
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<p> <p>See also <a href="#isEmpty">isEmpty</a>().
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<p>Example: <a href="customlayout-example.html#x1522">customlayout/card.cpp</a>.
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<h3 class=fn>type * <a name="current"></a>QPtrListIterator::current () const
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</h3>
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<p> Returns a pointer to the current iterator item. If the iterator is
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positioned before the first item in the list or after the last
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item in the list, 0 is returned.
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<p>Examples: <a href="canvas-example.html#x2949">canvas/canvas.cpp</a>, <a href="customlayout-example.html#x1523">customlayout/card.cpp</a>, and <a href="customlayout-example.html#x1481">customlayout/flow.cpp</a>.
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<h3 class=fn>bool <a name="isEmpty"></a>QPtrListIterator::isEmpty () const
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</h3>
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<p> Returns TRUE if the list is empty; otherwise returns FALSE.
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<p> <p>See also <a href="#count">count</a>().
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<h3 class=fn><a name="operator-type-*"></a>QPtrListIterator::operator type * () const
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</h3>
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<p> Cast operator. Returns a pointer to the current iterator item.
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Same as <a href="#current">current</a>().
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<h3 class=fn>type * <a name="operator()"></a>QPtrListIterator::operator() ()
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</h3>
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<p> Makes the succeeding item current and returns the original current
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item.
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<p> If the current iterator item was the last item in the list or if
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it was 0, 0 is returned.
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<h3 class=fn>type * <a name="operator*"></a>QPtrListIterator::operator* ()
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</h3>
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<p> Asterisk operator. Returns a pointer to the current iterator item.
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Same as <a href="#current">current</a>().
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<h3 class=fn>type * <a name="operator++"></a>QPtrListIterator::operator++ ()
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</h3>
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<p> Prefix ++ makes the succeeding item current and returns the new
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current item.
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<p> If the current iterator item was the last item in the list or if
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it was 0, 0 is returned.
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<h3 class=fn>type * <a name="operator+-eq"></a>QPtrListIterator::operator+= ( uint jump )
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</h3>
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<p> Sets the current item to the item <em>jump</em> positions after the
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current item and returns a pointer to that item.
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<p> If that item is beyond the last item or if the list is empty, it
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sets the current item to 0 and returns 0
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<h3 class=fn>type * <a name="operator--"></a>QPtrListIterator::operator-- ()
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</h3>
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<p> Prefix - makes the preceding item current and returns the new
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current item.
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<p> If the current iterator item was the first item in the list or if
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it was 0, 0 is returned.
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<h3 class=fn>type * <a name="operator--eq"></a>QPtrListIterator::operator-= ( uint jump )
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</h3>
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<p> Returns the item <em>jump</em> positions before the current item or 0
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if it is beyond the first item. Makes this the current item.
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<h3 class=fn><a href="qptrlistiterator.html">QPtrListIterator</a><type> & <a name="operator-eq"></a>QPtrListIterator::operator= ( const <a href="qptrlistiterator.html">QPtrListIterator</a><type> & it )
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</h3>
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<p> Assignment. Makes a copy of the iterator <em>it</em> and returns a
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reference to this iterator.
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<h3 class=fn>type * <a name="toFirst"></a>QPtrListIterator::toFirst ()
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</h3>
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<p> Sets the current iterator item to point to the first list item and
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returns a pointer to the item. Sets the current item to 0 and
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returns 0 if the list is empty.
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<p> <p>See also <a href="#toLast">toLast</a>() and <a href="#atFirst">atFirst</a>().
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<h3 class=fn>type * <a name="toLast"></a>QPtrListIterator::toLast ()
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</h3>
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<p> Sets the current iterator item to point to the last list item and
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returns a pointer to the item. Sets the current item to 0 and
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returns 0 if the list is empty.
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<p> <p>See also <a href="#toFirst">toFirst</a>() and <a href="#atLast">atLast</a>().
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<!-- eof -->
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<hr><p>
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This file is part of the <a href="index.html">Qt toolkit</a>.
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Copyright © 1995-2007
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<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
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<table width=100% cellspacing=0 border=0><tr>
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<td>Copyright © 2007
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<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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<td align=right><div align=right>Qt 3.3.8</div>
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</table></div></address></body>
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</html>
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