CODEWITHSUNDEEP
c++
rookie
rookie

Reputation: 7863

implementation of string class

I'm interested in the implementation of the reverse iterator with rbegin(), rend() and operator++ of the class string, I can't find it in google, how can I do it? thanks in advance for any help or any link

Upvotes: 2

Views: 261

Answers (3)

visitor
visitor

Reputation: 8834

Reverse iteration for bidirectional iterators is implemented in the std::reverse_iterator template.

The implementation of reverse iterators for std::string doesn't take more than:

template <xxx>
class basic_string
{
public:
    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
    typedef std::reverse_iterator<iterator> reverse_iterator;

    reverse_iterator rbegin() { return reverse_iterator(this->end()); }
    const_reverse_iterator rbegin() const { return const_reverse_iterator(this->end()); }
    reverse_iterator rend() { return reverse_iterator(this->begin()); }
    const_reverse_iterator rend() const { return const_reverse_iterator(this->begin()); }
    //...
};

(Copied from GCC's implementation.)

Upvotes: 0

Matthieu M.
Matthieu M.

Reputation: 299810

There is a basic implementation of reverse_iterator in the STL.

It is templatized by the Iterator to be reverted.

The idea is quite simple, if you look at a range:

[first, second, .... last]
   ^                         ^
 begin                      end
 rend                     rbegin

There is extra-work done, compared to a pure reverse iterator using this implementation, since for each dereference, you need to copy the iterator you hold, decrement it, and then dereference it.

Upvotes: 0

Oliver Charlesworth
Oliver Charlesworth

Reputation: 272497

You could look in the implementation header files. (e.g. /usr/include/c++/4.1.2/string on Linux). This will typically just pull in a load of other headers where the real meat lies, such as bits/basic_string.h.

I don't know where they reside for e.g. VC++, but you can usually just get Intellisense to find it by creating a std::string, selecting it and pressing F12.

Upvotes: 4

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