如何便携式是相比的qsort折返qsort_r功能? [英] How portable is the re-entrant qsort_r function compared to qsort?
问题描述
qsort_r()
是的重入版本的qsort()
这需要一个额外的'咚'的说法并将其传递到比较功能,我想能在移植的C code使用它。 的qsort()
是POSIX和无处不在,但 qsort_r()
似乎是一个BSD延伸。作为一个具体的问题,这是否存在,或者在Windows的C运行时等效?
qsort_r()
is the re-entrant version of qsort()
which takes an additional 'thunk' argument and passes it into the compare function and I'd like to be able to use it in portable C code. qsort()
is POSIX and everywhere but qsort_r()
seems to be a BSD extension. As a specific question, does this exist or have an equivalent in the Windows C runtime?
推荐答案
我试图写一个例子所示qsort_r / qsort_s(称为sort_r)的一个便携版本。我也把这个code在混帐回购协议( https://github.com/noporpoise/sort_r )
I've attempted to write a portable version of qsort_r / qsort_s (called sort_r) shown with an example. I've also put this code in a git repo (https://github.com/noporpoise/sort_r)
struct sort_r_data
{
void *arg;
int (*compar)(const void *a1, const void *a2, void *aarg);
};
int sort_r_arg_swap(void *s, const void *aa, const void *bb)
{
struct sort_r_data *ss = (struct sort_r_data*)s;
return (ss->compar)(aa, bb, ss->arg);
}
void sort_r(void *base, size_t nel, size_t width,
int (*compar)(const void *a1, const void *a2, void *aarg), void *arg)
{
#if (defined _GNU_SOURCE || defined __GNU__ || defined __linux__)
qsort_r(base, nel, width, compar, arg);
#elif (defined __APPLE__ || defined __MACH__ || defined __DARWIN__ || \
defined __FREEBSD__ || defined __BSD__ || \
defined OpenBSD3_1 || defined OpenBSD3_9)
struct sort_r_data tmp;
tmp.arg = arg;
tmp.compar = compar;
qsort_r(base, nel, width, &tmp, &sort_r_arg_swap);
#elif (defined _WIN32 || defined _WIN64 || defined __WINDOWS__)
struct sort_r_data tmp = {arg, compar};
qsort_s(*base, nel, width, &sort_r_arg_swap, &tmp);
#else
#error Cannot detect operating system
#endif
}
实例:
#include <stdio.h>
/* comparison function to sort an array of int, inverting a given region
`arg` should be of type int[2], with the elements
representing the start and end of the region to invert (inclusive) */
int sort_r_cmp(const void *aa, const void *bb, void *arg)
{
const int *a = aa, *b = bb, *p = arg;
int cmp = *a - *b;
int inv_start = p[0], inv_end = p[1];
char norm = (*a < inv_start || *a > inv_end || *b < inv_start || *b > inv_end);
return norm ? cmp : -cmp;
}
int main()
{
/* sort 1..19, 30..20, 30..100 */
int arr[18] = {1, 5, 28, 4, 3, 2, 10, 20, 18, 25, 21, 29, 34, 35, 14, 100, 27, 19};
/* Region to invert: 20-30 (inclusive) */
int p[] = {20, 30};
sort_r(arr, 18, sizeof(int), sort_r_cmp, p);
int i;
for(i = 0; i < 18; i++) printf(" %i", arr[i]);
printf("\n");
}
编译/运行/输出:
Compile/run/output:
$ gcc -Wall -Wextra -pedantic -o sort_r sort_r.c
$ ./sort_r
1 2 3 4 5 10 14 18 19 29 28 27 25 21 20 34 35 100
我已经在Mac和放大器测试; Linux操作系统。如果你发现错误/改进,请更新此code。您可以自由使用这个code,如你所愿。
I've tested on mac & linux. Please update this code if you spot mistakes / improvement. You are free to use this code as you wish.
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