AMDG Jeremiah Willcock wrote:
(Resubmitting to Boost list because I did not receive any answers on boost-users, nor any helpful answers on the Boost list.)
I would like to sort two separate vectors of numbers, treating corresponding elements of the two vectors as tuples and sorting the tuples. In particular, I am only comparing the first elements of the tuples; that may or may not be relevant to my problem. An example program is:
<snip>
On gcc 4.0.1, the sort operation results in the element (2, 1) (a pair of corresponding elements in a and b) being duplicated, while the element (1, 5) does not appear in the result at all:
Before: (0, 1) (2, 1) (1, 5) (2, 3) (4, 7) After: (0, 1) (2, 1) (2, 1) (2, 3) (4, 7)
I suspect the problem is related to the fact that zip_iterator does not return a "real" reference when dereferenced. Am I mistaken about this?
You are correct.
Is the code above supposed to work?
No.
If not, is there an alternative way to sort one sequence while swapping elements in another in a corresponding way? I am not able to join the two input sequences into a single sequence of pairs because of other factors in the use case for this code. Thank you for your help.
std::sort requires a Random Access Iterator. zip_iterator is not a Random Access Iterator. In Christ, Steven Watanabe