Re: removing duplicates from container,

From:

Mark P <usenet@fall2005REMOVE.fastmailCAPS.fm>

Newsgroups:

comp.lang.c++

Date:

Wed, 05 Jul 2006 18:02:23 GMT

Message-ID:

<P8Tqg.62113$fb2.43684@newssvr27.news.prodigy.net>

mlimber wrote:

vsgdp wrote:

I have a container of pointers. It is possible for two pointers to point to
the same element. I want to remove duplicates.

I am open to which container is best for this.

I thought of using std::set, but my elements do not have a '<' operator, as
it does not make sense. I could add an integer index to the data structure
so that each element has a unique index associated with it and then override
'<' to sort by index, but I am not sure if this is the best way.

Any advice appreciated.

Why can't you use std::set again? You could simply use addresses (i.e.
the value held by the pointer) as your sorting criterion. No duplicates
would be allowed (or did you mean the pointers could be different but
the pointees the same?). E.g.,

struct S { /*...*/ };
std::set<S*> ss; // Ok

Cheers! --M

A set would work fine, especially if you need to maintain at all times
the no-duplicates condition. If you only need to process the data once
or occasionally to remove all duplicates, you can use a vector, sort it,
and then remove duplicates. Look at std::sort and std::unique or
std::unique_copy.

Mark