一个c语言函数怎么实现给人以类型的数据排序?
用一个c语言函数怎么实现给任意类型的数据记录排序
函数参数有4个:指向实参的指针,实参记录的总长度,实参数据类型的长度(如int 为4字节),函数指针.
其中函数指针是一个指向比较函数的指针,用于比较记录的大小,返回值有负值,0,正直,分别对应大于,等于,小于. c语言
[解决办法]
用qsort函数：
QSORT(3) Linux Programmer's Manual QSORT(3)
NAME
qsort - sorts an array
SYNOPSIS
#include <stdlib.h>
void qsort(void *base, size_t nmemb, size_t size,
int(*compar)(const void *, const void *));
DESCRIPTION
The qsort() function sorts an array with nmemb elements of size size.
The base argument points to the start of the array.
The contents of the array are sorted in ascending order according to a
comparison function pointed to by compar, which is called with two
arguments that point to the objects being compared.
The comparison function must return an integer less than, equal to, or
greater than zero if the first argument is considered to be respec‐
tively less than, equal to, or greater than the second. If two members
compare as equal, their order in the sorted array is undefined.
RETURN VALUE
The qsort() function returns no value.
CONFORMING TO
SVr4, 4.3BSD, C89, C99.
NOTES
Library routines suitable for use as the compar argument include alpha‐
sort(3) and versionsort(3). To compare C strings, the comparison func‐
tion can call strcmp(3), as shown in the example below.
EXAMPLE
For one example of use, see the example under bsearch(3).
Another example is the following program, which sorts the strings given
in its command-line arguments:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static int
cmpstringp(const void *p1, const void *p2)
{
/* The actual arguments to this function are "pointers to
pointers to char", but strcmp(3) arguments are "pointers
to char", hence the following cast plus dereference */
return strcmp(* (char * const *) p1, * (char * const *) p2);
}
int
main(int argc, char *argv[])
{
int j;
if (argc < 2) {
fprintf(stderr, "Usage: %s <string>...\n", argv[0]);
exit(EXIT_FAILURE);
}
qsort(&argv[1], argc - 1, sizeof(argv[1]), cmpstringp);
for (j = 1; j < argc; j++)
puts(argv[j]);
exit(EXIT_SUCCESS);
}
SEE ALSO
sort(1), alphasort(3), strcmp(3), versionsort(3)
COLOPHON
This page is part of release 3.24 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2009-09-15 QSORT(3)
