stl vector reverse method

[Vasileios Zografos]

Hi there I am using the STL vector and I was wondering, is there an
existing method for reversing the contents of one vector?

e.g. vector<int> v1 which has entries 1,2,3,4,5
and I want to end up with v1=5,4,3,2,1 or perhaps leave v1 intact and
generate a new vector v2=5,4,3,2,1

so, does the STL have something allready? or do I have to do it manualy?

Thanks
V.Z.

[Sam Holden]

Re: stl vector reverse method

On Tue, 24 Jun 2003 03:32:41 +0100,
Vasileios Zografos <vzografos@bcs. org.uk> wrote:[color=blue]
> Hi there I am using the STL vector and I was wondering, is there an
> existing method for reversing the contents of one vector?
>
> e.g. vector<int> v1 which has entries 1,2,3,4,5
> and I want to end up with v1=5,4,3,2,1 or perhaps leave v1 intact and
> generate a new vector v2=5,4,3,2,1
>
> so, does the STL have something allready? or do I have to do it manualy?[/color]

std::reverse(v1 .begin(), v1.end());

or:

std::vector<wha tever> v2(v1.size());
std::reverse_co py(v1.begin(), v1.end(), v2.begin());

Surely you have a book with this stuff in it?

Or even: http://www.sgi.com/tech/stl/

--
Sam Holden

[Vasileios Zografos]

Re: stl vector reverse method

> Surely you have a book with this stuff in it?

Nope. But can you suggest one?

Thank you for the help.
V.Z.

[John Harrison]

Re: stl vector reverse method


"Vasileios Zografos" <vzografos@bcs. org.uk> wrote in message
news:bd8gip$3nm $1@news8.svr.po l.co.uk...[color=blue][color=green]
> > Surely you have a book with this stuff in it?[/color]
>
> Nope. But can you suggest one?
>
> Thank you for the help.
> V.Z.
>[/color]

The Standard C++ library by Josuttis.

[Michiel Salters]

Re: stl vector reverse method

sholden@flexal. cs.usyd.edu.au (Sam Holden) wrote in message news:<slrnbffee e.cah.sholden@f lexal.cs.usyd.e du.au>...[color=blue]
> On Tue, 24 Jun 2003 03:32:41 +0100,
> Vasileios Zografos <vzografos@bcs. org.uk> wrote:[color=green]
> > Hi there I am using the STL vector and I was wondering, is there an
> > existing method for reversing the contents of one vector?
> >
> > e.g. vector<int> v1 which has entries 1,2,3,4,5
> > and I want to end up with v1=5,4,3,2,1 or perhaps leave v1 intact and
> > generate a new vector v2=5,4,3,2,1
> >
> > so, does the STL have something allready? or do I have to do it manualy?[/color]
>
> std::reverse(v1 .begin(), v1.end());
>
> or:
>
> std::vector<wha tever> v2(v1.size());
> std::reverse_co py(v1.begin(), v1.end(), v2.begin());[/color]

The latter can also be written as

std::vector< > v2( v1.rbegin(), v1.rend() );

which saves v1.size() default-initializations of whatevers (which might
be impossible, default ctors aren't mandatory)

Regards,
--
Michiel Salters

[John Harrison]

Re: stl vector reverse method

> >[color=blue][color=green]
> > std::vector<wha tever> v2(v1.size());
> > std::reverse_co py(v1.begin(), v1.end(), v2.begin());[/color]
>
> The latter can also be written as
>
> std::vector< > v2( v1.rbegin(), v1.rend() );
>
> which saves v1.size() default-initializations of whatevers (which might
> be impossible, default ctors aren't mandatory)
>
> Regards,
> --
> Michiel Salters[/color]

Default ctors are mandatory to be compliant with the STL.

john

[Ron Natalie]

Re: stl vector reverse method


"John Harrison" <john_andronicu s@hotmail.com> wrote in message news:bd9u6r$qaj 1r$1@ID-196037.news.dfn cis.de...
[color=blue][color=green]
> > which saves v1.size() default-initializations of whatevers (which might
> > be impossible, default ctors aren't mandatory)
> >
> > Regards,
> > --
> > Michiel Salters[/color]
>
> Default ctors are mandatory to be compliant with the STL.[/color]

Default constructors are NOT mandatory. The requirement is that the contents
be copy constructable and assignable. The few functions that need to be able
to create "defaulted" objects take a parameter (defaulted to a default constructed
object) that is copied to these objects. If you provide a non-default constructed
object for these functions, your object does not need default constructor.