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## Function template integer_sort

boost::sort::spreadsort::integer_sort — Integer sort algorithm using random access iterators with just right-shift functor. (All variants fall back to `boost::sort::pdqsort` if the data size is too small, < `detail::min_sort_size`).

## Synopsis

    // In header: <boost/sort/spreadsort/integer_sort.hpp>

    template<typename RandomAccessIter, typename Right_shift>
      void integer_sort(RandomAccessIter first, RandomAccessIter last,
                        Right_shift shift);

## Description

`integer_sort` is a fast templated in-place hybrid radix/comparison algorithm, which in testing tends to be roughly 50% to 2X faster than `std::sort` for large tests (>=100kB).

Performance: Worst-case performance is O(N * (lg(range)/s + s)) , so `integer_sort` is asymptotically faster than pure comparison-based algorithms. `s` is `max_splits`, which defaults to 11, so its worst-case with default settings for 32-bit integers is O(N * ((32/11) slow radix-based iterations fast comparison-based iterations).
Some performance plots of runtime vs. n and log(range) are provided:
windows_integer_sort
osx_integer_sort

| Warning
Throwing an exception may cause data loss. This will also throw if a small vector resize throws, in which case there will be no data loss.

| Warning
Invalid arguments cause undefined behaviour.

| Note
`spreadsort` function provides a wrapper that calls the fastest sorting algorithm available for a data type, enabling faster generic-programming.

The lesser of O(N*log(N)) comparisons and O(N*log(K/S + S)) operations worst-case, where:

* N is `last` - `first`,

* K is the log of the range in bits (32 for 32-bit integers using their full range),

* S is a constant called max_splits, defaulting to 11 (except for strings where it is the log of the character size).

Parameters: |
`first` | Iterator pointer to first element.
`last` | Iterator pointing to one beyond the end of data.
`shift` | A functor that returns the result of shifting the value_type right a specified number of bits.
Requires: | [`first`, `last`) is a valid range.
Requires: | `RandomAccessIter` `value_type` is mutable.
Requires: | `RandomAccessIter` `value_type` is LessThanComparable
Postconditions: | The elements in the range [`first`, `last`) are sorted in ascending order.
Throws: | std::exception Propagates exceptions if any of the element comparisons, the element swaps (or moves), the right shift, subtraction of right-shifted elements, functors, or any operations on iterators throw.