箭头操作符和点操作符

[baolishicool]

看了c++ 《primer 4th edition》 关于箭头和点操作符的用法。
说箭头操作符用在指针身上，点操作符是用在对象身上。
但是他的书本上的以下实例中却这样用： (*beg)->remMsg(this); 文中的beg是迭代器，迭代器本身应该就是个指针！那么解引用后就是对象了！这时应该用(*beg).remMsg(this); 或者beg->remMsg(this)才对吧？会不会是书本的实例错了呢？还是我理解上有错误呢?请大家指教！

-------------------------------------以下是课本正文-----------------------
The remove_Msg_from_Folders Member
The implementation of the remove_Msg_from_Folders function is similar to that of put_Msg_in_Folders, except that this time we'll call remMsg to remove this Message from each Folder pointed to by folders:

// remove this Message from corresponding Folders
void Message::remove_Msg_from_Folders()
{
// remove this message from corresponding folders
for(std::set<Folder*>::const_iterator beg =
folders.begin (); beg != folders.end (); ++beg)
(*beg)->remMsg(this); // *beg points to a Folder
}


-----------------------------------------------------------------------

[sduxiaoxiang]

*beg的内容是Folder*吧
还是指针

[macrojj]

迭代器解引用 然后就是容器的元素 在这里是Folder*
所以用->
没有问题

[fox000002]

可以理解为

beg --> Folder**

*beg --> Floder*

*beg 取得的是容器装里的类型，而其类型是 Floder *

[Lstyk]

folders的成员本来就是指针啊，

        std::set <Folder*>::const_iterator beg = folders.begin ()

迭代器解引用后是set "folders"的成员，它的成员是Folder *类型的

[baolishicool]

[Quote=引用 1 楼 sduxiaoxiang 的回复:]
*beg的内容是Folder*吧
还是指针
[/Quote]
====================================
哦！我明白了！但是访问static成员为什么却可以把箭头操作符用在对象上？

Using a Class static Member
A static member can be invoked directly from the class using the scope operator or indirectly through an object, reference, or pointer to an object of its class type.

Account ac1;
Account *ac2 = &ac1;
// equivalent ways to call the static member rate function
double rate;
rate = ac1.rate(); // through an Account object or reference
rate = ac2->rate(); // through a pointer to an Account object
rate = Account::rate(); // directly from the class using the scope operator

[蜗牛大锅锅]

#include <set>
#include <iostream>

using namespace std;

struct Data
{
Data(int id): m_Id(id)
{
}
int m_Id;
};

typedef set<Data *> DataSet;

void main()
{
DataSet dset;
Data d1(1);
Data d2(2);

// dset存储的是Data *类型
dset.insert(&d1);
dset.insert(&d2);

// 迭代器取出来的是存储的数据Data *类型
DataSet::iterator it = dset.begin();
cout << ((*it)->m_Id) << endl;
Data *tmp = *it;
cout << (tmp->m_Id) << endl;
}

迭代器指向的是存储进去的数据的类型Folder*类型，访问Folder*当然要用指针拉

[baolishicool]

谢谢各位！