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POC++ standard template library priority queue throws exception with message "Invalid Heap"
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  1. POC++ standard template library priority queue throws exception with message "Invalid Heap"
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    copied!<p>Using the STL's <code>priority_queue</code> I get the error "invalid heap" as soon as I try to use <code>pop()</code>. I can push my values into the queue, the <code>top()</code> of the queue is what I would expect and accessible. <code>pop()</code>, when it goes to re-heap, seems to have a problem.</p> <p>I am storing pointers to a templated class in the queue. I have the comparision overloaded:</p> <pre><code>template &lt;class type&gt; class vertexPriorityCompare { public: bool operator()(Vertex&lt;type&gt;* leftVertex, Vertex&lt;type&gt;* rightVertex) const { if(leftVertex-&gt;getDistanceFromSource() &lt; 0 &amp;&amp; rightVertex-&gt;getDistanceFromSource() &lt; 0) { return false; } else if(leftVertex-&gt;getDistanceFromSource() &lt; 0) { return true; } else if(rightVertex-&gt;getDistanceFromSource() &lt; 0) { return false; } else { return leftVertex-&gt;getDistanceFromSource() &gt; rightVertex-&gt;getDistanceFromSource(); } } }; </code></pre> <p>The <code>priority_queue</code> is a private member of a class:</p> <pre><code>priority_queue&lt; Vertex&lt;type&gt;*, vector&lt; Vertex&lt;type&gt;* &gt;, vertexPriorityCompare&lt;type&gt; &gt; Q; </code></pre> <p>The overload works in the fashion it does, because a negative distance is considered infinity, always larger than whatever else; to represent infinity, distances are initialized to -1. The queue needs to keep the smallest, but non-negative at the top.</p> <p>I dereference the pointers in the overload, is what I'm doing there allowable? And, is there another operator I need to overload?</p> <p>I would attach code, but it seems if I do, it scares people away. Request to see more and I'll attach to another message.</p> <p>I dynamically declare an array of pointers to pointers, these are what get pushed, because I assume <code>priority_queue</code> stores by reference, so if I just put a pointer declared in the loop into the queue, that pointer goes out of scope. These pointers point to the proper <code>Vertex&lt;type&gt;</code>, and exist throughout the function.</p> <p>Visual Studio 2008 debugger takes me into 'stdthrow.cpp' line 24.</p>
 

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