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POC++ - LNK2019 error unresolved external symbol [template class's constructor and destructor] referenced in function _main
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copied!<p>[[UPDATE]] -> If I #include "Queue.cpp" in my program.cpp, it works just fine. This shouldn't be necessary, right?</p> <p>Hey all -- I'm using Visual Studio 2010 and having trouble linking a quick-and-dirty Queue implementation. I started with an <em>empty</em> Win32 Console Application, and all files are present in the project. For verbosity, here's the complete code to duplicate my error. I realize some of the code may, in fact, be wrong. I haven't had a chance to test it yet because I haven't yet been able to link it.</p> <p>Queue.hpp</p> <pre><code>#ifndef ERROR_CODE #define ERROR_CODE enum Error_Code { Success, Underflow, Overflow }; #endif // ERROR_CODE #ifndef QUEUE #define QUEUE template<class T> struct Queue_Node { T data; Queue_Node *next; Queue_Node() { next = NULL; } Queue_Node(T pData) { data = pData; next = NULL; } Queue_Node(T pData, Queue_Node *pNext) { data = pData; next = pNext; } }; template<class T> class Queue { public: Queue(); Error_Code Serve(); Error_Code Append(T item); T Front(); ~Queue(); private: void Rescursive_Destroy(Queue_Node<T> *entry); Queue_Node<T> *front, *rear; }; #endif // QUEUE </code></pre> <p>Queue.cpp</p> <pre><code>#include "Queue.hpp" template <class T> Queue<T>::Queue() { this->front = this->rear = NULL; } template<class T> Error_Code Queue<T>::Serve() { if(front == NULL) return Underflow; Queue_Node *temp = this->front; this->front = this->front->next; delete temp; } template<class T> Error_Code Queue<T>::Append(T item) { Queue_Node *temp = new Queue_Node(item); if(!temp) return Overflow; if(this->rear != NULL) this->rear->next = temp; this->rear = temp; return Success; } template<class T> T Queue<T>::Front() { if(this->front == NULL) return Underflow; return this->front->data; } template<class T> Queue<T>::~Queue() { this->Rescursive_Destroy(this->front); } template<class T> void Queue<T>::Rescursive_Destroy(Queue_Node<T> *entry) { if(entry != NULL) { this->Recursive_Destroy(entry->next); delete entry; } } </code></pre> <p>program.cpp</p> <pre><code>#include "Queue.hpp" int main() { Queue<int> steve; return 0; } </code></pre> <p>And the errors...</p> <pre><code>Error 1 error LNK2019: unresolved external symbol "public: __thiscall Queue<int>::~Queue<int>(void)" (??1?$Queue@H@@QAE@XZ) referenced in function _main C:\[omitted]\Project2_2\Project2_2\program.obj Project2_2 Error 2 error LNK2019: unresolved external symbol "public: __thiscall Queue<int>::Queue<int>(void)" (??0?$Queue@H@@QAE@XZ) referenced in function _main C:\[omitted]\Project2_2\Project2_2\program.obj Project2_2 </code></pre>

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