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POIterating multiple lists consecutively (C++)
 

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  1. POIterating multiple lists consecutively (C++)
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    <p>I have 3 classes, 2 inheriting from the other like so:</p> <pre><code>class A { public: virtual void foo() {cout &lt;&lt; "I am A!" &lt;&lt; endl;} }; class B : public A { public: void foo() {cout &lt;&lt; "B pretending to be A." &lt;&lt; endl} void onlyBFoo() {cout &lt;&lt; "I am B!" &lt;&lt; endl} }; class C : public A { public: void foo() {cout &lt;&lt; "C pretending to be A." &lt;&lt; endl} void onlyCFoo() {cout &lt;&lt; "I am C!" &lt;&lt; endl} }; </code></pre> <p>What I want to do is something like this:</p> <pre><code>list&lt;A*&gt; list_of_A; list&lt;B*&gt; list_of_B; list&lt;C*&gt; list_of_C; //put three of each class in their respective list cout &lt;&lt; "First loop:" &lt;&lt; endl; for (list&lt;B&gt;::iterator it = list_of_B.begin(); it != list_of_B.end(); ++it) { (*it)-&gt;onlyBFoo(); } cout &lt;&lt; "Second loop:" &lt;&lt; endl; for (list&lt;C&gt;::iterator it = list_of_C.begin(); it != list_of_C.end(); ++it) { (*it)-&gt;onlyCFoo(); } //This part I am not sure about cout &lt;&lt; "Third loop:" &lt;&lt; endl; for (Iterate all 3 loops i.e. *it points to As, then Bs then Cs) { (*it)-&gt;foo(); } </code></pre> <p>To output:</p> <pre><code>First loop: I am B! I am B! I am B! Second loop: I am C! I am C! I am C! Third loop: I am A! I am A! I am A! B pretending to be A. B pretending to be A. B pretending to be A. C pretending to be A. C pretending to be A. C pretending to be A. </code></pre> <p>i.e. sometimes I want to only iterate the B objects, but sometimes I want to iterate all the objects.</p> <p>One solution would be to store them all in a list, however I want to be able to loop through them in order of type i.e. the As then the Bs then the Cs.</p> <p>Another suggested solution was to use iterators or iterator_adapters, however I have never used them before and can't find a simple example to help me get started with them.</p>
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    1. USGraham Rogers
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    1. COYou want to iterate over a list of `A`, `B` and `C` objects in one loop, and on each object call a different function. Do I understand you correctly?
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      1. USwilhelmtell
    2. COAre you aware that `it->foo()` is equivalent to (and preferred over) `(*it).foo()`?
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      1. USMark Rushakoff
    3. CO@wilhelm - not quite - sometimes I want to loop over all the Bs and call functions only B has, and sometimes I want to loop over all the As and its subclasses, and call functions inherited/overridden from A i.e. separate loops. I have reworded the question to be a bit more clear what I want.
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      1. USGraham Rogers
 

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