Sounds like a job for std::copy_if. Define a predicate that keeps track of elements that already have been processed and return false if they have.
If you don’t have C++11 support, you can use the clumsily named std::remove_copy_if and invert the logic.
This is an untested example:
template <typename T>
struct NotDuplicate {
bool operator()(const T& element) {
return s_.insert(element).second; // true if s_.insert(element);
}
private:
std::set<T> s_;
};
Then
std::vector<int> uniqueNumbers;
NotDuplicate<int> pred;
std::copy_if(numbers.begin(), numbers.end(),
std::back_inserter(uniqueNumbers),
std::ref(pred));
where an std::ref
has been used to avoid potential problems with the algorithm internally copying what is a stateful functor, although std::copy_if
does not place any requirements on side-effects of the functor being applied.