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POC++, Xcode. Same error every time i try and use classes
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copied!<p>Every time I have a class in a header file and I'm using the class in the source file, I get the same error. Doesn't matter which class or which project it is.</p> <p>I am trying to insert a new node onto the head of a linked list data structure.</p> <p>Right now I have a pretty simple header file <code>main.h</code>:</p> <pre><code>namespace linkedlistofclasses { class Node { public: Node(); Node(int value, Node *next); //Constructor to initialize a node int getData() const; //Retrieve value for this node Node *getLink() const; //Retrieve next Node in the list void setData(int value); //Use to modify the value stored in the list void setLink(Node *next); //Use to change the reference to the next node private: int data; Node *link; }; typedef Node* NodePtr; } </code></pre> <p>My source file <code>main.cpp</code> looks like this:</p> <pre><code>#include <iostream> #include "main.h" using namespace std; using namespace linkedlistofclasses; void head_insert(NodePtr &head, int the_number) { NodePtr temp_ptr; //The constructor sets temp_ptr->link to head and //sets the data value to the_number temp_ptr = new Node(the_number, head); head = temp_ptr; } int main() { NodePtr head, temp; //Create a list of nodes 4->3->2->1->0 head = new Node(0, NULL); for (int i = 1; i < 5; i++) { head_insert(head, i); } //Iterate through the list and display each value temp = head; while (temp !=NULL) { cout << temp->getData() << endl; temp = temp->getLink(); } //Delete all nodes in the list before exiting //the program. temp = head; while (temp !=NULL) { NodePtr nodeToDelete = temp; temp = temp->getLink(); delete nodeToDelete; } return 0; } </code></pre> <p>My problem is that I get these compilation errors: </p> <pre><code>Undefined symbols for architecture x86_64: "linkedlistofclasses::Node::Node(int, linkedlistofclasses::Node*)", referenced from: head_insert(linkedlistofclasses::Node*&, int) in main.o _main in main.o "linkedlistofclasses::Node::getData() const", referenced from: _main in main.o "linkedlistofclasses::Node::getLink() const", referenced from: _main in main.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation) </code></pre> <p>If I run the code without a using a class, writing everything in the source file <code>main.cpp</code>, there is no problem. But no matter how I write a class, I always get some variant of this error. </p>

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