C++ 在.h文件中使用带有结构的模板，得到未知错误

尝试制作自定义数组列表，第一个错误告诉我将类型Tamplate（）添加到结构ListNode中。

但是在遵循错误指令后，反而得到了新的错误。

" 找不到建筑x86_64符号

 #ifndef LINKEDLIST_H
 #define LINKEDLIST_H
 #include <iostream>
 #include <string>
  using namespace std;
 template<typename T>
 struct ListNode<T>{
       T value;
       ListNode<T>* next;
       ListNode(T d,ListNode<T> *n){
       value = d;
       next = n;
     }
 };

 template<typename T>
 class LinkedList
 {
 public :
     LinkedList();
     LinkedList(const LinkedList<T>& another);
      ~LinkedList();
     void copy(const LinkedList<T>& another);
     void add(T value);
     void remove(int index);
     int get(int index) const;
     bool isEmpty() const;
     int size() const;
     string toString() const;
     void clear();
     LinkedList<T>& operator = (const LinkedList<T>& another);
 private :
     ListNode<T>* x_front;
     int x_size;
 };
 #endif // LINKEDLIST_H

..CPP

 #include "linkedlist.h"
 #include "strlib.h"
 #include <string>
 using namespace std;
 template<typename T>
 LinkedList<T>::LinkedList(){
       x_front = NULL;
       x_size =0;
 }
 template<typename T>
 LinkedList<T>::~LinkedList(){
     clear();
 }
 template<typename T>
 LinkedList<T>& LinkedList<T>::operator = (const LinkedList<T>& another){
     delete x_front;
     copy(another);
     return *this;
 }
 template<typename T>
 void LinkedList<T>::copy(const LinkedList<T>& another){
      ListNode<T>* anotherCurrent = another.x_front;
      while(anotherCurrent!=NULL){
          this->add(anotherCurrent->value);
          anotherCurrent = anotherCurrent->next;
       }
 }
 template<typename T>
 void LinkedList<T>::add(T value){
     if(x_front == NULL){
         x_front = new ListNode<T>(value,NULL);
     }
     else {
         ListNode<T>*current = x_front;
         while(current-> next != NULL){
             current = current -> next;
         }
         current->next = new ListNode<T>(value,NULL);
     }
     x_size++;
 }
 template<typename T>
 void LinkedList<T>::remove(int index){
     if(index==0){
         x_front = x_front->next;
     }

 else  {
           ListNode<T>* current = x_front;
           for(int indexNow = 0 ; indexNow < index -1 ; indexNow++){
                                            current = current->next;
           }
           current -> next = current -> next -> next;
    }
    x_size--;
}

template<typename T>
bool LinkedList<T>::isEmpty() const {
    if(this->x_size == 0){
        return true;
    }
    else {return false;}
}
template<typename T>
void LinkedList<T>::clear(){
    while(this->isEmpty() ==false){
        remove(x_size-1);
    }
}
template<typename T>
string LinkedList<T>::toString() const{
    string mystring;
    for(ListNode<T>*p = x_front; p!=NULL ;p = p->next){
        mystring = mystring + " " + integerToString(p->value);
    }
    return mystring;
}
template<typename T>
int LinkedList<T>::size() const{
      return (this->x_size);
}