CODEWITHSUNDEEP
c++stliteratorc++11
void-pointer
void-pointer

Reputation: 14827

C++11: Nonmember rbegin()/rend() Functions

Since the nonmember begin() and end() functions were added for standard contains in the C++11 revision, why have the nonmember versions of the rbegin() and rend() functions not been added as well? I feel silly after beginning to use the nonmember versions of begin() and end(), only to find that I now have to toggle between the using the member and nonmember function calls. (I realize that it would be trivial to roll my own nonmember versions of rbegin() and rend(), but I'm wondering why this wasn't added to the standard).

Thanks for your input.

Upvotes: 17

Views: 2348

Answers (2)

Polymer
Polymer

Reputation: 1063

For people who see this later, nonmember rbegin() and rend() are already in C++14.

Upvotes: 7

Potatoswatter
Potatoswatter

Reputation: 137890

You can construct reversed range by manually using std::reverse_iterator on the results of std::begin and std::end.

Oddly, there is not a standard factory function for reverse_iterator. If there were, it would probably look like this:

template< typename iter >
std::reverse_iterator< iter > reverse( iter i )
    { return { i }; }

Armed with this, you can do

std::sort( reverse( std::end( my_array ) ), reverse( std::begin( my_array ) ) );

This example saves the trouble of specifying the std::greater comparator, but the reverse_iterator conceivably could adversely affect performance if the compiler can't remove the added complexity from inner loops.

Upvotes: 5

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