Choose type of iterator which fits your container: input, output, forward etc. Use base iterator classes from standard library. For example, std::iterator with random_access_iterator_tag.These base classes define all type definitions required by STL and do other work. To avoid code duplication iterator class should be a template class and be parametrized by "value type", "pointer type", "reference type" or all of them (depends on implementation). For example: // iterator class is parametrized by pointer type template <typename PointerType> class MyIterator { // iterator class definition goes here }; typedef MyIterator<int*> iterator_type; typedef MyIterator<const int*> const_iterator_type; Notice iterator_type and const_iterator_type type definitions: they are types for your non-const and const iterators.

参见:标准库参考

EDIT: std::iterator自c++ 17起已弃用。请在这里查看相关讨论。

我不知道Boost有没有什么有用的东西。

我喜欢的模式很简单:取一个模板参数，它等于value_type，无论是否有const限定。如果需要，还可以使用节点类型。然后，好吧，一切都有条不紊了。

只需要记住参数化(模板化)所有需要的东西，包括复制构造函数和operator==。在大多数情况下，const的语义将创建正确的行为。

template< class ValueType, class NodeType >
struct my_iterator
 : std::iterator< std::bidirectional_iterator_tag, T > {
    ValueType &operator*() { return cur->payload; }

    template< class VT2, class NT2 >
    friend bool operator==
        ( my_iterator const &lhs, my_iterator< VT2, NT2 > const &rhs );

    // etc.

private:
    NodeType *cur;

    friend class my_container;
    my_iterator( NodeType * ); // private constructor for begin, end
};

typedef my_iterator< T, my_node< T > > iterator;
typedef my_iterator< T const, my_node< T > const > const_iterator;

Choose type of iterator which fits your container: input, output, forward etc. Use base iterator classes from standard library. For example, std::iterator with random_access_iterator_tag.These base classes define all type definitions required by STL and do other work. To avoid code duplication iterator class should be a template class and be parametrized by "value type", "pointer type", "reference type" or all of them (depends on implementation). For example: // iterator class is parametrized by pointer type template <typename PointerType> class MyIterator { // iterator class definition goes here }; typedef MyIterator<int*> iterator_type; typedef MyIterator<const int*> const_iterator_type; Notice iterator_type and const_iterator_type type definitions: they are types for your non-const and const iterators.

参见:标准库参考

EDIT: std::iterator自c++ 17起已弃用。请在这里查看相关讨论。

我偶然看到这篇文章，很惊讶这里没有提到一个简单的方法。使用std::iterator所描述的指向值的指针显然是一种非常通用的方法。但是你可以用一些更简单的方法。当然，这是一种简单的方法，可能并不总是足够的，但如果是的话，我将它发布给下一个读者。

类中的底层类型很可能是一个STL容器，它已经为你定义了迭代器。如果是这样的话，你可以简单地使用他们定义的迭代器，而不需要创建自己的迭代器。

这里有一个例子:

class Foo {

  std::vector<int>::iterator begin() { return data.begin(); }
  std::vector<int>::iterator end() { return data.end(); }

  std::vector<int>::const_iterator begin() const { return data.begin(); }
  std::vector<int>::const_iterator end() const { return data.end(); }


private:
  std::vector<int> data

};

他们经常忘记iterator必须转换为const_iterator，而不是相反。这里有一个方法:

template<class T, class Tag = void>
class IntrusiveSlistIterator
   : public std::iterator<std::forward_iterator_tag, T>
{
    typedef SlistNode<Tag> Node;
    Node* node_;

public:
    IntrusiveSlistIterator(Node* node);

    T& operator*() const;
    T* operator->() const;

    IntrusiveSlistIterator& operator++();
    IntrusiveSlistIterator operator++(int);

    friend bool operator==(IntrusiveSlistIterator a, IntrusiveSlistIterator b);
    friend bool operator!=(IntrusiveSlistIterator a, IntrusiveSlistIterator b);

    // one way conversion: iterator -> const_iterator
    operator IntrusiveSlistIterator<T const, Tag>() const;
};

在上面注意如何将IntrusiveSlistIterator<T>转换为IntrusiveSlistIterator<T const>。如果T已经是const，则此转换永远不会被使用。

我有兴趣知道这是如何正确的，但似乎工作作为一个滚动您自己的迭代器内部数据存储

template<typename T>
struct iterator_type
{
    using self_type             = iterator_type;
    using iterator_category     = std::random_access_iterator_tag;
    using difference_type       = std::ptrdiff_t;
    using value_type            = std::remove_cv_t<T>;
    using pointer               = T*;
    using reference             = T&;

    iterator_type( pointer ptr ) noexcept
        : _ptr{ ptr }
    {}

    reference operator*() noexcept { return *_ptr; }
    pointer operator->() noexcept { return _ptr; }

    self_type operator++() noexcept { ++_ptr; return *this; }
    self_type operator++(int) noexcept { self_type tmp = *this; ++_ptr; return tmp; }

    self_type operator--() noexcept { --_ptr; return *this; }
    self_type operator--(int) noexcept { self_type tmp = *this; --_ptr; return tmp; }

    bool operator==( const self_type &other ) const noexcept { return _ptr == other._ptr; }
    bool operator!=( const self_type &other ) const noexcept { return _ptr != other._ptr; }

private:
    pointer _ptr;
};


template<typename T>
using const_iterator_type = iterator_type<std::add_const_t<T>>;

然后我只是把这些添加到我的类，似乎工作如预期。

template<typename T>
class Container
{
public:
    using iterator               = iterator_type<T>;
    using const_iterator         = const_iterator_type<T>;
    using reverse_iterator       = std::reverse_iterator<iterator>;
    using const_reverse_iterator = std::reverse_iterator<const_iterator>;

...

    iterator begin() { return _begin; }
    iterator end() { return _begin + _size; }

    const_iterator cbegin() const { return _begin; }
    const_iterator cend() const { return _begin + _size; }

    reverse_iterator rbegin() { return reverse_iterator(_begin + _size); }
    reverse_iterator rend() { return reverse_iterator(_begin); }

    const_reverse_iterator crbegin() const { return const_reverse_iterator(_begin + _size); }
    const_reverse_iterator crend() const { return const_reverse_iterator(_begin); }

private:
    T*         _begin;
    size_t     _size;
    size_t     _capacity;
};

唯一的事情是，使它与std::cbegin()， std::rcbegin()， std::cend()和std::rcend()函数，我必须扩展std命名空间:

namespace std
{
    template<typename T>
    typename Container<T>::const_iterator cbegin( Container<T> &c ) { return c.cbegin(); }

    template<typename T>
    typename Container<T>::const_iterator cend( Container<T> &c ) { return c.cend(); }

    template<typename T>
    typename Container<T>::const_reverse_iterator crbegin( Container<T> &c ) { return c.crbegin(); }

    template<typename T>
    typename Container<T>::const_reverse_iterator crend( Container<T> &c ) { return c.crend(); }
}