using std::sort;

**John Harrison** · Jul 22 '05, 06:37 AM

Re: using std::sort;

"alexhong20 01" <alexhong2001@h otmail.com> wrote in message
news:sGaYb.3286 8$hR.817769@bgt nsc05-news.ops.worldn et.att.net...[color=blue]
> Does "std::sort" work only with sequence containers, not associative
> containers at all?[/color]

All the standard associative containers are already sorted.
[color=blue]
>
> Among sequential containers, can it be used with "list", "queue" and other
> sequence containers besides "vector"?[/color]

It can only be used with containers that have random access iterators. Among
the standard containers list means vector and deque, it can also be used
with arrays. List has its own sort method. Queue is not a container but a
container adapter, it modifies the interface of another container. If you
need to sort a container then queue isn't for you.
[color=blue]
>
> Are "istringstr eam" and "ostringstr eam" covered in the book, "STL Tutorial
> and Reference" (second edition) by D. Musser, et al.? Seems like I could
> not find any related topic in the book.
>
> Thanks for your comments!
>[/color]

john

**David Harmon** · Jul 22 '05, 06:37 AM

Re: using std::sort;

On Mon, 16 Feb 2004 21:33:12 GMT in comp.lang.c++, "alexhong20 01"
<alexhong2001@h otmail.com> was alleged to have written:[color=blue]
>Does "std::sort" work only with sequence containers, not associative
>containers at all?[/color]

Associative containers always keep themselves sorted according to the
predicate they were created with, in order to facilitate finding things.
They cannot be re-sorted differently.
[color=blue]
>Among sequential containers, can it be used with "list", "queue" and other
>sequence containers besides "vector"?[/color]

std::sort() requires random access iterators (Stroustrup sect. 18.7.1).
std::list provides bidirectional iterators so std::sort Not Applicable.
std::list provides it's own list::sort() method (Stroustrup 17.2.2.1).
[color=blue]
>Are "istringstr eam" and "ostringstr eam" covered in the book, "STL Tutorial
>and Reference" (second edition) by D. Musser, et al.? Seems like I could
>not find any related topic in the book.[/color]

Wouldn't surprise me. The STL portion of the standard library usually
refers to the part derived from the work of Stepanov, which doesn't
include streams and std::string.

**David Fisher** · Jul 22 '05, 06:37 AM

Re: using std::sort;

"alexhong20 01" <alexhong2001@h otmail.com> asked:
[color=blue]
> Does "std::sort" work only with sequence containers, not associative
> containers at all?
> Among sequential containers, can it be used with "list", "queue" and other
> sequence containers besides "vector"?[/color]

std::sort() requires a pair of "random access iterators" - which applies to
std::vector, std::deque and array types (int x[20], etc), but not lists. The
std::list template class has its own custom sorting function, also called
sort().

If you want a sorted queue, you might want to use std::deque instead of
std:queue.

AFAIK, std::set and std::map elements are stored in sorted order.

David F

**rossum** · Jul 22 '05, 06:37 AM

Re: using std::sort;

On Mon, 16 Feb 2004 21:42:32 -0000, "John Harrison"
<jahhajATntlwor ldDOTcom@remove .this> wrote:
[color=blue]
>
>"alexhong200 1" <alexhong2001@h otmail.com> wrote in message
>news:sGaYb.328 68$hR.817769@bg tnsc05-news.ops.worldn et.att.net...[color=green]
>> Does "std::sort" work only with sequence containers, not associative
>> containers at all?[/color]
>
>All the standard associative containers are already sorted.
>[color=green]
>>
>> Among sequential containers, can it be used with "list", "queue" and other
>> sequence containers besides "vector"?[/color]
>
>It can only be used with containers that have random access iterators. Among
>the standard containers list means vector and deque, it can also be used
>with arrays. List has its own sort method. Queue is not a container but a
>container adapter, it modifies the interface of another container. If you
>need to sort a container then queue isn't for you.[/color]
Not a queue, but perhaps a priority_queue might fit the requirement.
A priority_queue is automatically sorted by priority so it does not
have an explicit sort operation.

rossum
[color=blue]
>[color=green]
>>
>> Are "istringstr eam" and "ostringstr eam" covered in the book, "STL Tutorial
>> and Reference" (second edition) by D. Musser, et al.? Seems like I could
>> not find any related topic in the book.
>>
>> Thanks for your comments!
>>[/color]
>
>john
>[/color]

--

The Ultimate Truth is that there is no Ultimate Truth

**Claudio Puviani** · Jul 22 '05, 06:37 AM

Re: using std::sort;

"David Harmon" <source@netcom. com> wrote[color=blue]
> On Mon, 16 Feb 2004 21:33:12 GMT in comp.lang.c++, "alexhong20 01"
> <alexhong2001@h otmail.com> was alleged to have written:[color=green]
> >Does "std::sort" work only with sequence containers, not associative
> >containers at all?[/color]
>
> Associative containers always keep themselves sorted according to the
> predicate they were created with, in order to facilitate finding things.
> They cannot be re-sorted differently.[/color]

Just to avoid confusion, it's not associative containers in general that are
sorted by the key, but only some specific types. Hash maps and sets are not
sorted by key, but they are associative containers.

Claudio Puviani

P.S.: I'm not singling you out, David. It just doesn't make sense to reply the
same thing to everyone. ;-)

**Rob Williscroft** · Jul 22 '05, 06:38 AM

Re: using std::sort;

Claudio Puviani wrote in
news:pMfYb.2655 6$cE3.25848082@ news4.srv.hcvln y.cv.net:
[color=blue]
> "David Harmon" <source@netcom. com> wrote[color=green]
>> On Mon, 16 Feb 2004 21:33:12 GMT in comp.lang.c++, "alexhong20 01"
>> <alexhong2001@h otmail.com> was alleged to have written:[color=darkred]
>> >Does "std::sort" work only with sequence containers, not associative
>> >containers at all?[/color]
>>
>> Associative containers always keep themselves sorted according to the
>> predicate they were created with, in order to facilitate finding
>> things. They cannot be re-sorted differently.[/color]
>
> Just to avoid confusion, it's not associative containers in general
> that are sorted by the key, but only some specific types. Hash maps
> and sets are not sorted by key, but they are associative containers.
>
> Claudio Puviani
>
> P.S.: I'm not singling you out, David. It just doesn't make sense to
> reply the same thing to everyone. ;-)
>[/color]

The confusion arises as acording to the Standard "Associativ e Containers"
are sorted:

<quote>
23.1.2/9

The fundamental property of iterators of associative containers is
that they iterate through the containers in the non-descending order
of keys where non-descending is defined by the comparison that was
used to construct them. For any two dereferenceable iterators i and j
such that distance from i to j is positive, value_comp(*j, *i) == false
</quote>

Presumably when we get unordered_set<> etc the Standard will introduce
a new concept "Unordered Associative Container" or some such.

Rob.
--

http://www.victim-prime.dsl.pipex.com/

using std::sort;

using std::sort;

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