Reverse Iteration of an STL Algorithm

Question

I have a function that is being called with 2 pointers for arguments, the beginning and and ending of an array. My function will search from the end pointer to the beginning pointer for an element that matches a condition.

If I was trying to iterate forward I could do this with find_if but I need to iterate in reverse. Does the STL have any provision for this?

Note: I can easily do this in a for loop. What I'm looking for is a more elegant solution.

Answer 1

Yes, it is called std::reverse_iterator. An example:

template<typename RandomAccessIterator>
void reverse_sort(RandomAccessIterator begin, RandomAccessIterator end) {
    typedef std::reverse_iterator<RandomAccessIterator> r_iter_t;
    std::sort(r_iter_t(end), r_iter_t(begin));
}

int main() {
    int arr[] = { 1, 2, 3 };
    reverse_sort(std::begin(arr), std::end(arr));
    for(auto i : arr) std::cout << i << "\n";
}

gives

3
2
1