调用方法，并传入指向类的指针

Question

I'm trying to call a method to add to an object to a vector within another object. I'm getting the error;

'': Illegal use of this type as an expression

Within my program I declare an object to store my node in the main;

accountStream *accountStore = new accountStream;

Then call the function;

new_account(&accountStore);

The new_account function is as;

void new_account(accountStream &accountStorage)
{
    newAccount *account = new newAccount;
    (&accountStorage)->pushToStore(account);
}

The account stream class has a vector that receives it, but there is where my error is;

class accountStream
{
public:
    accountStream();
    ~accountStream();

    template <class account>
    void pushToStore(account);

private:
    std::vector <newAccount*> accountStore;
};

template<class account>
inline void accountStream::pushToStore(account)
{
    accountStore.push_back(account);
}

The error is on the second last line;

accountStore.push_back(account);

I've got a feeling it's something to do with the way I'm passing the object into the method, but after messing around for a while I haven't been able to pinpoint where exactly I've gone wrong.

Answer 1

2 problems:

1. new_account(&accountStore); is wrong, use new_account(*accountStore); to match the argument type.

2. accountStore.push_back(account); is wrong. account is type not object. Add some argument to the function.

Answer 2

Several issues:

1. You must specify the variable name here (and not only the type):

    template<class account> inline void accountStream::pushToStore(account c) { accountStore.push_back(c); } 

2. You must receive a pointer (not a reference to a pointer) here

    void new_account(accountStream *accountStorage) { newAccount *account = new newAccount; accountStorage->pushToStore(account); } 

3. You must call the function with a pointer as a parameter:

    new_account(accountStore); 

   Alternatively, you can declare the variable (not a pointer to):

    accountStream accountStore; 

   call the function:

    new_account(accountStore); 

   and receive a reference:

    void new_account(accountStream &accountStorage) { newAccount *account = new newAccount; accountStorage.pushToStore(account); } 

Answer 3

As answered here already, you need to use *accountStore and not &accountStore because the function takes a reference and not a pointer to a pointer (which is what you get from using & operator on a pointer).

the second problem is here:

template<class account>
inline void accountStream::pushToStore(account)
{
    accountStore.push_back(account);
}

you are declaring the function templated on the 'account' therefore account is a type, and what you are trying to do in the next line is push_back a type and not an object. the correct code would be:

template<class account>
inline void accountStream::pushToStore(account acct)
{
    accountStore.push_back(acct);
}

because account is the type while acct is an instance of the type account.