将对象添加到链接列表错误[C ++]

Question

I am attempting to add an object to a Linked List structure but keep receiving this error in Visual Studio 2015:

Error   LNK2019 unresolved external symbol "public: void __thiscall Stack::add(class Creature *)" (?add@Stack@@QAEXPAVCreature@@@Z) referenced in function _main    

Here is my code to add to the list - this functions fine if I modify it to simply add an integer value to a linked list(not allowed to use the STL):

#include "Creature.h"

void Stack::add(Creature* obj) {
    /* create head node if list is empty */
    if (head == NULL) {
        head = new Node;
        head->data = obj;
        head->next = NULL;
    }
    else {
        /* set pointer to head */
        Node* temp = head;

        /* iterate until next node is empty */
        while (temp->next != NULL)
            temp = temp->next;

        /* create new node when NULL */
        temp->next = new Node;
        temp->next->data = obj;
        temp->next->next = NULL;
    }
}

Here is my Creature class definition (abstract class):

class Creature {
    protected:
        int strike, defense,
            armor, strength,
            damage;
        bool alive;
        string type;
    public:
        Creature(
                strike = 0;
                defense = 0;
                armor = 0;
                strength = 0;
                alive = true;
                type = " ";
                );
        virtual int attack() = 0;
        virtual bool defend(int) = 0;
        virtual string name() = 0;
};

And here is my main function where I attempt to add the object to the list:

#include "Stack.h"
#include "Creature.h"
#include "Barbarian.h"

int main() {
    Stack q;
    Creature *test = new Barbarian;
    q.add(test);
    return 0;
}

I am still pretty fresh to C++ so I am trying to learn everything that I can and attempt to figure things out on my own first before asking for help, but I just cannot see what I may be missing here. Any help/resources would be greatly appreciated!

Answer 1

The error LNK 2019 is because of "A function or variable is declared but not defined." But as you mention in the above you have defined the stack::add definition. Then it might be not added to your current project and hence it will not find the definition.

In Visual Studio solution tree right click on the project then Add -> Existing item -> choose the source file (I guess in your case it is stack.cpp)

Answer 2

看来我已经解决了，我继续前进，咬了一下子句，只是删除了项目，然后重新导入了文件。