Calling std::list::erase(iterator pos) with a reverse_iterator?

[Dalbosco J-F]

Hi,

Sorry if this has already been answered.

Given a std::list and a reverse_iterator is there a way to erase the
element pointed to by the reverse_iterator via the erase method?
Apparently the erase method takes a normal iterator and it fails to
compile if I pass it a reverse_iterator. On the other hand, I don't
wan't to use myList.remove( *(myReverseIterator)) for performance reason.

Can anyone help?
Thanks by advance,
JF.

 

[Azumanga]

Hi,

Sorry if this has already been answered.

Given a std::list and a reverse_iterator is there a way to erase the
element pointed to by the reverse_iterator via the erase method?
Apparently the erase method takes a normal iterator and it fails to
compile if I pass it a reverse_iterator. On the other hand, I don't
wan't to use myList.remove( *(myReverseIterator)) for performance reason.

reverse_iterator has a method called "base" which will give you back
the base iterator. You can use this.

Chris

 

[Azumanga]

Hi,

Sorry if this has already been answered.

Given a std::list and a reverse_iterator is there a way to erase the
element pointed to by the reverse_iterator via the erase method?
Apparently the erase method takes a normal iterator and it fails to
compile if I pass it a reverse_iterator. On the other hand, I don't
wan't to use myList.remove( *(myReverseIterator)) for performance reason.

Apologises for two posts in a short period of time, I just realised my
previous post had an error.

In the standard, you'll notice that:

Iterator base() const; returns "current", while operator* is defined
as:

" iterator tmp = current; return *--tmp;"

Therefore, *reverse_it and *(reverse_it.base()) aren't the same thing.
*reverse_it and *(--reverse_it.base()) are.

Reverse iterators are strange..

Chris

 

[Marcus Kwok]

Reverse iterators are strange..

Here's a good article that explains the relationships among the
different types of iterators:

http://www.ddj.com/dept/cpp/184401406