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POC++ Inheritance and how to pass and maintain subclass data through a superclass
 

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    <p>Alright, wasn't quite sure how to word the question and couldn't find any duplicates that I think really address this situation.</p> <p>Essentially I have a super class that gets extra data appended to it through a subclass. The container class for this data recognizes only the super class and adjust characteristics based on an id parameter in the super class.</p> <p>I've actually never had to used inheritance in c++ till recently so forgive me if this is trivial. I'm under the impression that when I go to hard copy a bunch of data using the superclass, the subclass data is loss in translation so to speak. In order to bypass this limitation I'm trying to use a typecast-ed pointer however I now get a segmentation fault when trying to free the memory even when typecasting the pointer parameter in the free() function.</p> <p>Here is the sample code...</p> <p>Structs</p> <pre><code>// Super class struct Vertex { __declspec(align(4)) unsigned int vType; // Identifies the vertex type. Vertex(const unsigned int _vType) : vType(_vType) { } Vertex(const Vertex &amp;_rV) : vType(_rV.vType) { } // Copy constructor virtual ~Vertex() { } unsigned int GetVType() const { return vType; } }; // Subclass // Id = 1 struct V_Pos : Vertex { __declspec(align(4)) XMFLOAT3 position; V_Pos(void) : Vertex(1) { } V_Pos(XMFLOAT3 &amp;_rPosition) : Vertex(1), position(_rPosition) { } V_Pos(const V_Pos &amp;_rV) : Vertex(_rV), position(_rV.GetPosition()) { } // Copy constructor ~V_Pos() { } XMFLOAT3 GetPosition() const { return position; } }; </code></pre> <p>Here is how I'm currently copying the data.</p> <pre><code>// pBuffer is declared as a Vertex* data type pBuffer = new V_Pos[_bufSize]; if (_pVBuffer-&gt;GetVType() == 1) for (unsigned int i = 0; i &lt; bufSize; ++i) { V_Pos *_temp = (V_Pos*)&amp;_pVBuffer[i]; pBuffer[i] = *_temp; } </code></pre> <p>Here is how I am currently de-allocating the data.</p> <pre><code>if (pBuffer != 0) { delete [] pBuffer; pBuffer = 0; } </code></pre> <p>What is the correct approach for this situation?</p> <p><strong>Edit 1 -</strong></p> <p>Updated the above code blocks to clarify the comment discussion under knulp's answer.</p>
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    1. COWhy would you want to use a subclass to update its superclass?
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    2. CO@JAB - My hacky attempt to update the superclass with the subclass is in order to grab the appended subclass data. The whole vertex buffer is used as a BLOB that is fed to a COM object and then forgotten.
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