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From: bparker@gil.com.au (Brian Parker)
Subject: Re: "Modifying algorithms" aren't??
Date: 1997/05/28
Message-ID: <338cfe55.15140972@news.ipswich.gil.com.au>#1/1
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On 28 May 97 09:12:37 GMT, pedwards@cs.wright.edu (Phil Edwards)
wrote:

>CD2 doesn't specify one way or the other that I can find, but it seems
>that the HP-as-modified-for-DEC implementation of the algorithms in
>25.2, [lib.alg.modifying.operations], are behaving very non-intuitively.
>
>Specifically, "deleting" members of a container, by whatever method, only
>copies the remaining elements "up" a place in the container, leaving
>copies of the last element in the container.  It seems that this would be
>fine (lazy deallocation), BUT the extraneous copy at the end is still
>being included in the container's membership.
>
>As example, this:
>
>	deque<int>    foo;
>	for (int i=0; i<20; i++)  foo.push_back(i);
>
>	cerr << "Original foo:\n";
>	copy (foo.begin(), foo.end(), ostream_iterator<int>(cerr, " "));
>
>	remove (foo.begin(), foo.end(), 14);
>
>	cerr << "\n\nNew foo:\n";
>	copy (foo.begin(), foo.end(), ostream_iterator<int>(cerr, " "));
>	cerr << endl;
>
>results in:
>
>	Original foo:
>	0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 
>
>	New foo:
>	0 1 2 3 4 5 6 7 8 9 10 11 12 13 15 16 17 18 19 19 
>                                                       ^^-- ugh
>
>I realize that remove() and similar algorithms return "the end of the
>resulting range".
>...

With the iterator returned from remove( ), you can call erase( ) on
the deque itself to actually delete the elements.

(The generic algorithms, acting through iterators, don't have access
to the original container and so can't remove the elements from the
container)

,Brian Parker (bparker@gil.com.au)
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