Re: STL: how to get the sequence number of a newly added item into a set
"bilgekhan" <bilgekhan@bilgekhanbilgekhan.net.tr> wrote:
It sounds like you would be better served by using a std::vector
and sorting it (using std::sort,) then you can do lookups with
std::lower_bound, upper_bound, equal_range, and binary_search and
getting the "sequence number" is simply a matter of a little pointer
math.
I need to get the seqnbr for each item that gets added to
the sorted collection, so then especially the sorting would be an overkill.
Then don't. Use std::lower_bound to do all your insertions and you won't
have to use sort and will be able to find sequence numbers with ease.
Use the right tool for the job and the job will be much easier.
FYI: I'm doing this for the table-lookup routine (ie. a dictionary) of
a special data compressor for data records with common structure;
ie. it's not general purpose.
Maybe you should consider a std::map then.
I just want to make this last point clear: I just have pointed out
IMO a shortcoming, performance issues or missing features
of the language that I in the field have encountered.
It's of course up to the language and library designers to
understand the problem and to fix or implement the functionality.
I'm just informing the people who are more involved in such issues.
If I were the designer of the library I would do it the way I described above.
It is, of course, your prerogative to design classes however you want.
By all means make a container that implements a red-black tree *and*
keeps track of sequence numbers. Maybe in doing so, you will come to
understand why std::set doesn't work that way, or maybe you will build a
container that others are eager to use.