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| 6 | <meta name="generator" content="Docutils 0.3.9: http://docutils.sourceforge.net/" /> |
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| 7 | <title>Boost Pointer Container Library</title> |
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| 8 | <link rel="stylesheet" href="default.css" type="text/css" /> |
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| 9 | </head> |
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| 10 | <body> |
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| 11 | <div class="document" id="boost-pointer-container-library"> |
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| 12 | <h1 class="title"><img alt="Boost" src="boost.png" /> Pointer Container Library</h1> |
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| 13 | <h2 class="subtitle" id="examples">Examples</h2> |
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| 14 | <p>Some examples are given here and in the accompanying test files:</p> |
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| 15 | <div class="contents topic" id="contents"> |
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| 16 | <ul class="simple"> |
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| 17 | <li><a class="reference" href="#null-pointers-cannot-be-stored-in-the-containers" id="id1" name="id1">1. Null pointers cannot be stored in the containers</a></li> |
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| 18 | <li><a class="reference" href="#iterators-and-other-operations-return-indirected-values" id="id2" name="id2">2. Iterators and other operations return indirected values</a></li> |
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| 19 | <li><a class="reference" href="#copy-semantics-of-pointer-containers" id="id3" name="id3">3. Copy-semantics of pointer containers</a></li> |
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| 20 | <li><a class="reference" href="#making-a-non-copyable-type-clonable" id="id4" name="id4">4. Making a non-copyable type Clonable</a></li> |
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| 21 | <li><a class="reference" href="#objects-are-cloned-before-insertion-inserted-pointers-are-owned-by-the-container" id="id5" name="id5">5. Objects are cloned before insertion, inserted pointers are owned by the container</a></li> |
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| 22 | <li><a class="reference" href="#transferring-ownership-of-a-single-element" id="id6" name="id6">6. Transferring ownership of a single element</a></li> |
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| 23 | <li><a class="reference" href="#transferring-ownership-of-pointers-between-different-pointer-containers" id="id7" name="id7">7. Transferring ownership of pointers between different pointer containers</a></li> |
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| 24 | <li><a class="reference" href="#selected-test-files" id="id8" name="id8">8. Selected test files</a></li> |
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| 25 | </ul> |
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| 26 | </div> |
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| 27 | <span id="example-1"></span><div class="section" id="null-pointers-cannot-be-stored-in-the-containers"> |
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| 28 | <h1><a class="toc-backref" href="#id1" name="null-pointers-cannot-be-stored-in-the-containers">1. Null pointers cannot be stored in the containers</a></h1> |
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| 29 | <pre class="literal-block"> |
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| 30 | my_container.push_back( 0 ); // throws bad_ptr |
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| 31 | my_container.replace( an_iterator, 0 ); // throws bad_ptr |
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| 32 | my_container.insert( an_iterator, 0 ); // throws bad_ptr |
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| 33 | </pre> |
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| 34 | </div> |
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| 35 | <span id="example-2"></span><div class="section" id="iterators-and-other-operations-return-indirected-values"> |
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| 36 | <h1><a class="toc-backref" href="#id2" name="iterators-and-other-operations-return-indirected-values">2. Iterators and other operations return indirected values</a></h1> |
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| 37 | <pre class="literal-block"> |
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| 38 | ptr_vector<X> pvec; |
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| 39 | std::vector<X*> vec; |
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| 40 | *vec.begin() = new X; // fine, memory leak |
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| 41 | *pvec.begin() = new X; // compile time error |
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| 42 | ( *vec.begin() )->foo(); // call X::foo(), a bit clumsy |
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| 43 | pvec.begin()->foo(); // no indirection needed |
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| 44 | *vec.front() = X(); // overwrite first element |
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| 45 | pvec.front() = X(); // no indirection needed |
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| 46 | </pre> |
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| 47 | </div> |
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| 48 | <span id="example-3"></span><div class="section" id="copy-semantics-of-pointer-containers"> |
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| 49 | <h1><a class="toc-backref" href="#id3" name="copy-semantics-of-pointer-containers">3. Copy-semantics of pointer containers</a></h1> |
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| 50 | <pre class="literal-block"> |
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| 51 | ptr_vector<T> vec1; |
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| 52 | ... |
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| 53 | ptr_vector<T> vec2( vec1.clone() ); // deep copy objects of 'vec1' and use them to construct 'vec2', could be very expensive |
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| 54 | vec2 = vec1.release(); // give up ownership of pointers in 'vec1' and pass the ownership to 'vec2', rather cheap |
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| 55 | vec2.release(); // give up ownership; the objects will be deallocated if not assigned to another container |
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| 56 | vec1 = vec2; // compile time error: 'operator=()' not defined |
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| 57 | ptr_vector<T> vec3( vec1 ); // compile time error: copy-constructor not defined |
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| 58 | </pre> |
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| 59 | </div> |
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| 60 | <span id="example-4"></span><div class="section" id="making-a-non-copyable-type-clonable"> |
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| 61 | <h1><a class="toc-backref" href="#id4" name="making-a-non-copyable-type-clonable">4. Making a non-copyable type Clonable</a></h1> |
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| 62 | <pre class="literal-block"> |
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| 63 | // a class that has no normal copy semantics |
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| 64 | class X : boost::noncopyable { public: X* clone() const; ... }; |
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| 65 | |
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| 66 | // this will be found by the library by argument dependent lookup |
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| 67 | X* new_clone( const X& x ) |
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| 68 | { return x.clone(); } |
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| 69 | |
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| 70 | // we can now use the interface that requires clonability |
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| 71 | ptr_vector<X> vec1, vec2; |
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| 72 | ... |
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| 73 | vec2 = vec1.clone(); // 'clone()' requires cloning <g> |
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| 74 | vec2.insert( vec2.end(), vec1.begin(), vec1.end() ); // inserting always means inserting clones |
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| 75 | </pre> |
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| 76 | </div> |
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| 77 | <span id="example-5"></span><div class="section" id="objects-are-cloned-before-insertion-inserted-pointers-are-owned-by-the-container"> |
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| 78 | <h1><a class="toc-backref" href="#id5" name="objects-are-cloned-before-insertion-inserted-pointers-are-owned-by-the-container">5. Objects are cloned before insertion, inserted pointers are owned by the container</a></h1> |
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| 79 | <pre class="literal-block"> |
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| 80 | class X { ... }; // assume 'X' is Clonable |
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| 81 | X x; // and 'X' can be stack-allocated |
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| 82 | ptr_list<X> list; |
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| 83 | list.push_back( x ); // clone 'x' and then insert the resulting pointer |
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| 84 | list.push_back( new_clone( x ); // do it manually |
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| 85 | list.push_back( new X ); // always give the pointer directly to the container to avoid leaks |
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| 86 | list.push_back( &x ); // don't do this!!! |
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| 87 | </pre> |
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| 88 | </div> |
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| 89 | <span id="example-6"></span><div class="section" id="transferring-ownership-of-a-single-element"> |
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| 90 | <h1><a class="toc-backref" href="#id6" name="transferring-ownership-of-a-single-element">6. Transferring ownership of a single element</a></h1> |
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| 91 | <pre class="literal-block"> |
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| 92 | ptr_deque<T> deq; |
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| 93 | typedef ptr_deque<T>::auto_type auto_type; |
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| 94 | |
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| 95 | // ... fill the container somehow |
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| 96 | |
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| 97 | auto_type ptr = deq.release_back(); // remove back element from container and give up ownership |
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| 98 | auto_type ptr2 = deq.release( deq.begin() + 2 ); // use an iterator to determine the element to release |
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| 99 | ptr = deq.release_front(); // supported for 'ptr_list' and 'ptr_deque' |
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| 100 | </pre> |
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| 101 | </div> |
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| 102 | <span id="example-7"></span><div class="section" id="transferring-ownership-of-pointers-between-different-pointer-containers"> |
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| 103 | <h1><a class="toc-backref" href="#id7" name="transferring-ownership-of-pointers-between-different-pointer-containers">7. Transferring ownership of pointers between different pointer containers</a></h1> |
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| 104 | <pre class="literal-block"> |
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| 105 | ptr_list<X> list; ptr_vector<X> vec; |
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| 106 | ... |
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| 107 | // |
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| 108 | // note: no cloning happens in these examples |
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| 109 | // |
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| 110 | list.transfer( list.begin(), vec.begin(), vec ); // make the first element of 'vec' the first element of 'list' |
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| 111 | vec.transfer( vec.end(), list.begin(), list.end(), list ); // put all the lists element into the vector |
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| 112 | </pre> |
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| 113 | </div> |
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| 114 | <span id="example-8"></span><div class="section" id="selected-test-files"> |
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| 115 | <h1><a class="toc-backref" href="#id8" name="selected-test-files">8. Selected test files</a></h1> |
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| 116 | <table class="docutils field-list" frame="void" rules="none"> |
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| 117 | <col class="field-name" /> |
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| 118 | <col class="field-body" /> |
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| 119 | <tbody valign="top"> |
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| 120 | <tr class="field"><th class="field-name" colspan="2"><a class="reference" href="../test/incomplete_type_test.cpp">incomplete_type_test.cpp</a>:</th></tr> |
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| 121 | <tr><td> </td><td class="field-body">Shows how to implement the Composite pattern.</td> |
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| 122 | </tr> |
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| 123 | <tr class="field"><th class="field-name" colspan="2"><a class="reference" href="../test/simple_test.cpp">simple_test.cpp</a>:</th></tr> |
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| 124 | <tr><td> </td><td class="field-body">Shows how the usage of pointer container compares with a |
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| 125 | container of pointer pointers</td> |
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| 126 | </tr> |
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| 127 | <tr class="field"><th class="field-name" colspan="2"><a class="reference" href="../test/view_example.cpp">view_example.cpp</a>:</th></tr> |
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| 128 | <tr><td> </td><td class="field-body">Shows how to use a pointer container as a view into other container</td> |
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| 129 | </tr> |
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| 130 | <tr class="field"><th class="field-name"><a class="reference" href="../test/tree_test.cpp">tree_test.cpp</a>:</th><td class="field-body">Shows how to make a tree-structure</td> |
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| 131 | </tr> |
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| 132 | <tr class="field"><th class="field-name"><a class="reference" href="../test/ptr_array.cpp">array_test.cpp</a>:</th><td class="field-body">Shows how to make an n-ary tree</td> |
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| 133 | </tr> |
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| 134 | </tbody> |
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| 135 | </table> |
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| 136 | <!-- 9. A large example |
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| 137 | ++++++++++++++++++ |
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| 138 | |
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| 139 | This examples shows many of the most common |
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| 140 | features at work. |
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| 141 | |
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| 142 | .. raw:: html |
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| 143 | :file: tut1.html |
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| 144 | |
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| 145 | 10. Changing the Clone Allocator |
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| 146 | ++++++++++++++++++++++++++++++++ |
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| 147 | |
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| 148 | This example shows how we can change |
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| 149 | the Clone Allocator to use the pointer containers |
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| 150 | as view into other containers: |
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| 151 | |
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| 152 | .. raw:: html |
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| 153 | :file: tut2.html --> |
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| 154 | <p><strong>Navigate:</strong></p> |
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| 155 | <ul class="simple"> |
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| 156 | <li><a class="reference" href="ptr_container.html">home</a></li> |
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| 157 | <li><a class="reference" href="reference.html">reference</a></li> |
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| 158 | </ul> |
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| 159 | <table class="docutils field-list" frame="void" rules="none"> |
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| 160 | <col class="field-name" /> |
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| 161 | <col class="field-body" /> |
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| 162 | <tbody valign="top"> |
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| 163 | <tr class="field"><th class="field-name">copyright:</th><td class="field-body">Thorsten Ottosen 2004-2005.</td> |
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| 164 | </tr> |
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| 165 | </tbody> |
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| 166 | </table> |
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| 167 | </div> |
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| 168 | </div> |
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| 169 | </body> |
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| 170 | </html> |
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