CODEWITHSUNDEEP
c++overloading
codefx
codefx

Reputation: 10502

C++ const iterator in Vector

I am a newbie to C++. So, please bear with me. I was looking into the implementation of the std::vector class. I found the following 2 different implementation of the begin() method. I understand that the first one returns a RW iterator and the second one returns a read-only iterator. I thought that mere difference in return type is not enough for function overloading. How does this work then? 

iterator
begin()
{ return iterator(this->_M_impl._M_start); }

const_iterator
begin() const
{ return const_iterator(this->_M_impl._M_start); }

Upvotes: 1

Views: 769

Answers (2)

Mark Garcia
Mark Garcia

Reputation: 17708

One is const and the other isn't. The const version will be called for const std::vector objects while the other is called for non-const std::vector objects. Also note that this also applies to const and non-const references and pointers.

More info on const methods and overloading:

Also relevant:

Upvotes: 2

Emanuele Paolini
Emanuele Paolini

Reputation: 10162

The implicit "this" parameter is const in the second method. This is enough to distinguish them in overloading.

Upvotes: 0

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