Re: STL container question

From:

Richard Herring <junk@[127.0.0.1]>

Newsgroups:

comp.lang.c++

Date:

Thu, 2 Oct 2008 15:39:29 +0100

Message-ID:

<YOUi2ZRh0N5IFwBp@baesystems.com>

In message <gc26jq$ksb$1@ulysses.noc.ntua.gr>, Ioannis Vranos
<ivranos@no.spam.nospamfreemail.gr> writes

Juha Nieminen wrote:

Ioannis Vranos wrote:

Lists are implemented using pointers to point to the previous and to the
next elements, so list::sort(), is more efficient by changing pointer
values, while sorting a vector involves copying objects.

The original poster talked about storing integer values. I highly
doubt sorting a list of integers will be faster than sorting an array of
integers. In fact, I'm pretty sure of the contrary.

We must think generally. In general, sorting a list is faster than
sorting a vector, because the list sorting does not involve the
construction or destruction of any object.

So how many constructions and destructions does std::sort involve?

Regarding ints, I think sorting a vector of ints and as list of ints,
both have about the same efficiency.

How many integer assignments to swap two ints in a vector?
How many pointer assignments to swap two elements in a list?

If the programmer decides to replace ints with other objects, he will
not have to change much in the code, if he uses a list.

What would he have to change with a vector?

--
Richard Herring