gcc 编译以下代码没有错误。我正在创建一个可以与任何数据类型的数组一起使用的冒泡排序函数（因此是函数指针）。
它可以毫无问题地对字符串数组（arr2）进行排序，但是，我无法弄清楚为什么它不能正确地对整数数组（arr）进行排序。我在 compare_long 函数中添加了一条 printf 语句，以查看发生了什么。看起来整数没有正确传递给它。任何帮助将不胜感激。
#include <stdio.h>
#include <string.h>
#define MAX_BUF 256
long arr[10] = { 3,6,1,2,3,8,4,1,7,2};
char arr2[5][20] = { "Mickey Mouse",
"Donald Duck",
"Minnie Mouse",
"Goofy",
"Pluto" };
void bubble(void *p, int width, int N, int(*fptr)(const void *, const void *));
int compare_string(const void *m, const void *n);
int compare_long(const void *m, const void *n);
int main(void) {
int i;
puts("\nBefore Sorting:\n");
for(i = 0; i < 10; i++) { /* show the long ints */
printf("%ld ",arr[i]);
}
puts("\n");
for(i = 0; i < 5; i++) { /* show the strings */
printf("%s\n", arr2[i]);
}
bubble(arr, 4, 10, compare_long); /* sort the longs */
bubble(arr2, 20, 5, compare_string); /* sort the strings */
puts("\n\nAfter Sorting:\n");
for(i = 0; i < 10; i++) { /* show the sorted longs */
printf("%d ",arr[i]);
}
puts("\n");
for(i = 0; i < 5; i++) { /* show the sorted strings */
printf("%s\n", arr2[i]);
}
return 0;
}
void bubble(void *p, int width, int N, int(*fptr)(const void *, const void *)) {
int i, j, k;
unsigned char buf[MAX_BUF];
unsigned char *bp = p;
for(i = N - 1; i >= 0; i--) {
for(j = 1; j <= i; j++) {
k = fptr((void *)(bp + width*(j-1)), (void *)(bp + j*width));
if(k > 0) {
memcpy(buf, bp + width*(j-1), width);
memcpy(bp + width*(j-1), bp + j*width , width);
memcpy(bp + j*width, buf, width);
}
}
}
}
int compare_string(const void *m, const void *n) {
char *m1 = (char *)m;
char *n1 = (char *)n;
return (strcmp(m1,n1));
}
int compare_long(const void *m, const void *n) {
long *m1, *n1;
m1 = (long *)m;
n1 = (long *)n;
printf("m1 = %l and n1 = %l\n", *m1, *n1);
return (*m1 > *n1);
}