c++动态成员中存在未定义的引用错误

Question

大家好，我是编程新手，请原谅noob问题。。。我尝试了各种方法来处理未定义的引用错误，但它一直在向我抛出错误我试着使用指针"->"one_answers"：："符号以及点"。"我该怎么办？为什么它不能编译？

这是我的cpp文件：

#include <cstdlib>
#include "account.hpp"
using namespace std;
int Account::getAccountNumber()
    {
        return accountNumber;
    }
double Account::getBalance()
    {
        return balance;
    }
void Account::createAccount(LinkedList<Account>& accountsList, string name, int idNumber)
{
...
    case 1:
       accountsList.addFront(newAcc); //Where the error occurs.
        break;
    case 2:
        do
        {
            cout << "ntWhich position would you like to insert then"
                 << "tnew account into?n"
                 << "tPosition number: #";
            cin >> target;
            if (cin.fail())
            {
                cin.clear();
                cin.ignore(20,'n');
                cout << "nntSorry, wrong input. Please enter a correct position.nn";
                system("pause");
            }
        }
        while(cin.fail());
        accountsList.addMiddle(newAcc, target); //and here
        break;
    case 3:
        accountsList.addEnd(newAcc); //and here
        break;
    }
    cout << "nntAccount Created Successfullynn"
         << accountsList; 
    system("pause");
}

这是我的.hpp

#ifndef ACCOUNT_HPP_INCLUDED
#define ACCOUNT_HPP_INCLUDED
#include "linkedlist.hpp"
#include "generic.hpp"
class Account : public GenericAccount
{
    int accountNumber;
    double balance;
public:
    Account(string name = "empty", int idNumber = 0, int accountNumber = 0, double balance = 0)
        :  GenericAccount(name, idNumber), accountNumber(accountNumber), balance(balance) {}
    int getAccountNumber();
    double getBalance();
    void createAccount(LinkedList<Account>&, string, int);
    void deposit(LinkedList<Account>&, Account&);
    void withdraw(LinkedList<Account>&, Account&);
    void displayAccount(LinkedList<Account>&, Account&);
    void deleteAccount(LinkedList<Account>&);
    friend istream& operator>> (istream& is, Account& x)
    {
        is >> x.accountNumber;
        return is;
    }
    friend ostream& operator << (ostream& os, Account& c)
    {
        os << "Account Number= " << c.getAccountNumber() << "t"
           << "Balance= "<< c.getBalance() << endl;
        return os;
    }
    friend bool operator == (Account& a, Account& target)
    {
        return (a.getAccountNumber() == target.getAccountNumber());
    }
};

#endif // ACCOUNT_HPP_INCLUDED

完整的项目可以在这里下载以供参考提前感谢大家！

Answer 1

我认为问题是没有为帐户类型（实际上是任何类型）定义addFront方法。请参阅为什么模板只能在头文件中实现？以获得更好的解释。

将cpp的内容以内联方式移动到.h文件中就可以了。另一个选项是将.cpp文件重命名为.inl，并将其包含在linkedList.hpp 的底部