sort.h is an implementation a ton of sorting algorithms in C with a user-defined type that is defined at include time.

This means you don't have to pay the function call overhead of using standard library routine. This gives us the power of higher-level language generics.

In addition, you don't have to link in a library: the entirety of this sorting library is contained in the header files.

You get the choice of many sorting routines, including:

• Shell sort
• Binary insertion sort
• Heap sort
• Quick sort
• Merge sort (stable)
• In-place merge sort (not stable)
• Selection sort (ugh -- this is really only here for comparison)
• Tim sort (stable)

If you don't know which one to use, you should probably use Tim sort.

If you have a lot data that is semi-structured, then you should definitely use Tim sort.

If you have data that is really and truly random, quick sort is probably fastest.

To use this library, you need to do three things:

• #define SORT_TYPE to be the type of the elements of the array you want to sort. (For pointers, you should declare this like: #define SORT_TYPE int*)
• #define SORT_NAME to be a unique name that will be prepended to all the routines, i.e., #define SORT_NAME mine would give you routines named mine_heap_sort, and so forth.
• #include "sort.h". Make sure that sort.h and sort_common.h are in your include path.

Then, enjoy using the sorting routines.

Quick example:

#define SORT_NAME int64
#define SORT_TYPE int64_t
#define SORT_CMP(x, y) ((x) - (y))
#include "sort.h"

You would now have access to int64_quick_sort, int64_tim_sort, etc., which you can use like

/* Assumes you have some int *arr or int arr[128]; */
int64_quick_sort(arr, 128);

See demo.c for a more detailed example usage.

If you are going to use your own custom type, you must redefine SORT_CMP(x, y) with your comparison function, so that it returns a value less than zero if x < y, equal to zero if x == y, and greater than 0 if x > y.

The default just uses the builtin <, ==, and > operators:

#define SORT_CMP(x, y)  ((x) < (y) ? -1 : ((x) == (y) ? 0 : 1))

It is often just fine to just subtract the arguments as well (though this can cause some stability problems with floating-point types):

#define SORT_CMP(x, y) ((x) - (y))

The speed of each routine is highly dependent on your computer and the structure of your data.

If your data has a lot of partially sorted sequences, then Tim sort will beat the pants off of anything else.

Tim sort is not as good if memory movement is many orders of magnitude more expensive than comparisons (like, many more than for normal int and double). If so, then quick sort is probably your routine. On the other hand, Tim sort does extremely well if the comparison operator is very expensive, since it strives hard to minimize comparisons.

Here is the output of demo.c, which will give you the timings for a run of 10,000 int64_ts on 2014-era MacBook Pro:

Running tests
stdlib qsort time:             1157.00 us per iteration
stdlib heapsort time:          2323.00 us per iteration
stdlib mergesort time:         1381.00 us per iteration
quick sort time:                628.00 us per iteration
selection sort time:         115757.00 us per iteration
merge sort time:                733.00 us per iteration
binary insertion sort time:   10409.00 us per iteration
heap sort time:                 481.00 us per iteration
shell sort time:                774.00 us per iteration
tim sort time:                  729.00 us per iteration
in-place merge sort time:       658.00 us per iteration

Heap sort is the winner here. Quick sort, in-place merge sort, and tim sort also often tend to be quite fast.

Christopher Swenson ([email protected])

• Wikipedia
• timsort.txt (under doc/)

All code in this repository, unless otherwise specified, is hereby licensed under the MIT Public License:

Copyright (c) 2010-2014 Christopher Swenson.

Copyright (c) 2012 Google Inc. All Rights Reserved.

Copyright (c) 2012 Vojtech Fried.

In-place mergesort is:

Copyright (c) 2012, Andrey Astrelin, [email protected]

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.