need explanation for one line of code

[awais hec]

class const_iterator: public map< T, int >::const_iterator
{
.............
};

Currently i am reading Data Structures with C++ using STL. In the source code i found the above mentioned line of code but i do not understand the meaning of this line. Kindly explain this line.

[S6k9GNh0]

I'm guessing it's declaration of a const_iterator class extending the const_iterator class inside of the templated container, map.

[Hammurabi]

This part class const_iterator means you're declaring a class called const_iterator.

This part : public map< T, int >::const_iterator means you're using the const_iterator class nested in a map<T,int> as a base class.