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]

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?

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

or:

std::vector<whatever> v2(v1.size());
std::reverse_copy(v1.begin(), v1.end(), v2.begin());

Surely you have a book with this stuff in it?

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

 

[Vasileios Zografos]

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]

Nope. But can you suggest one?

Thank you for the help.
V.Z.

The Standard C++ library by Josuttis.

 

[Michiel Salters]

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

or:

std::vector<whatever> v2(v1.size());
std::reverse_copy(v1.begin(), v1.end(), v2.begin());

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,

 

[John Harrison]

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,

Default ctors are mandatory to be compliant with the STL.

john

 

[Ron Natalie]

Default ctors are mandatory to be compliant with the STL.

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.