Re: Problems removing an element from a std::set using a reverse_iterator

In article <1185287381.614903.61710@m3g2000hsh.googlegroups.com>,
irotas <google@irotas.net> wrote:


Safer and equivalent to your code is

UIntSet::reverse_iterator ri = std::find_if
   (
      uis.rbegin(),
      uis,rend(),
      std::bind2nd
      (
         std::less<unsigned int>(),
         THRESHOLD
      )
   );

// you now erase [uis.rbegin(),ri)
// ri.base points to next in forward sequence and uis.rbegin()
// points to r.end() that is you want to erase [ri.base(),uis.end())
// or
uis.erase(ri.base(),uis.end())

This should work with sequence containers of sorted data and
sorted assoc. containers.

I would expect that a vector<unsigned int> that is not sorted to
compare favorably if not surpass greatly the efficiency of set to
test just the erasure process.
std::vector<unsigned int> vec;
// fill vec
vec.erase
(
   remove_if(vec.begin(),vec.end(),erase_me()),
   vec.end()
);

is even more concise, this involve N compares and # to remove copies
and # to remove dtor calls. The copies and dtors are dirt cheap. so it
is N compares and they are cheap too most likely.

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