Question

我使用模板在c ++代码中实现了一个简单的列表实现。代码是这样的，有两个文件：

TestList.h ：

#pragma once
namespace Containers{
     template <class T> class TestList
     {
      public:
          TestList();
          ~TestList();
          void Append(T data);
      private:
          struct Node{
            struct Node * next;
            T data;
          };
          int m_count;
          Node * m_head;
     }
}

TestList.cpp ：

#include "TestList.h"
namespace Containers{
template<typename T>
    TestList<T>::TestList() : m_count(0), m_head(NULL)
    {
    }

    template<typename T>
    TestList<T>::~TestList()
    {
        if (this->m_head){
            Node * tmp = this->m_head;
            Node * prev = NULL;
            while (tmp->Next){
                prev = tmp;
                tmp = tmp->next;
                delete prev;
            }
        }
    }
    template<typename T>
    void TestList<T>::Append(T data)
    {
        Node * tmp = this->m_head;
        if (this->m_head){
            tmp = this->m_head;
            while (tmp->next){
                tmp = tmp->next;
            }
        }

        Node * item = new Node();
        item->data = data;
        if (tmp)
            tmp->next = item;
        else
            this->m_head = item;

        this->m_count++;

    }
}

所以这是一些小代码，我只是为了玩模板而编写的。然后在main.cpp中：

#include <Windows.h>
#include "TestList.h"

int main()
{
    Containers::TestList<const wchar_t *> list;

    list.Append(L"123");
    return 0;
}

当我尝试编译并运行时，出现如下链接错误：

LNK2019 unresolved external symbol "public: void __thiscall Containers::TestList<wchar_t const *>::Append(wchar_t const *)" (?Append@?$TestList@PB_W@Containers@@QAEXPB_W@Z) referenced in function _main
LNK2019 unresolved external symbol "public: __thiscall Containers::TestList<wchar_t const *>::TestList<wchar_t const *>(void)" (??0?$TestList@PB_W@Containers@@QAE@XZ) referenced in function _main
LNK2019 unresolved external symbol "public: __thiscall Containers::TestList<wchar_t const *>::~TestList<wchar_t const *>(void)" (??1?$TestList@PB_W@Containers@@QAE@XZ) referenced in function _main

所以我在.cpp文件中定义了T，但它仍然给我错误。到目前为止，我在此站点上尝试过建议的解决方案：

输入：

#include "TestList.h"

extern template class Containers::TestList<const wchar_t *>;
extern template Containers::TestList<const wchar_t *>;
extern Containers::TestList<const wchar_t *>;

int main()
{ 
   ...

c ++模板LNK2019：未解析的外部符号

0 个答案: