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The following README.md and sort_r.h files have been imported from the [noporpoise/sort_r Github project](https://github.com/noporpoise/sort_r) in order to provide a portable reentrant version of qsort.
sort_r
======
Isaac Turner 2013
Portable qsort_r / qsort_s
Discussion here: http://stackoverflow.com/questions/4300896/how-portable-is-the-re-entrant-qsort-r-function-compared-to-qsort
License: Public Domain - use as you wish, no warranty
[](https://travis-ci.org/noporpoise/sort_r)
About
-----
If you want to qsort() an array with a comparison operator that takes parameters
you need to use global variables to pass those parameters (not possible when
writing multithreaded code), or use qsort_r/qsort_s which are not portable
(there are separate GNU/BSD/Windows versions and they all take different arguments).
So I wrote a portable qsort_r/qsort_s called sort_r():
void sort_r(void *base, size_t nel, size_t width,
int (*compar)(const void *a1, const void *a2, void *aarg),
void *arg);
`base` is the array to be sorted
`nel` is the number of elements in the array
`width` is the size in bytes of each element of the array
`compar` is the comparison function
`arg` is a pointer to be passed to the comparison function
Using sort_r
------------
Add `#include "sort_r.h"` to the top of your code. Then copy sort_r.h into your
working directory, or add -I path/to/sort_r to your compile arguments.
Build Example
-------------
Compile example code (`example.c`) with:
make
To build using nested functions and qsort instead of qsort_r use
make NESTED_QSORT=1
Nested functions are not permitted under ISO C, they are a GCC extension.
License
-------
Public Domain. Use as you wish. No warranty. There may be bugs.
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