#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
/** Our old friend die from ex17. */
void die(const char *message)
{
if (errno) {
perror(message);
} else {
printf("ERROR: %s\n", message);
}
exit(1);
}
//a typedef creates a fake type, int this
// case for a function pointer
typedef int (*compare_cb) (int a, int b);
/**
*
* A classsic bubble sort function that uses the
* compare_cb to do the sorting.
*/
int *bubble_sort(int *numbers, int count, compare_cb cmp)
{
int temp = 0;
int i = 0;
int j = 0;
int *target = malloc(count * sizeof(int));
if (!target)
die("Memory error.");
memcpy(target, numbers, count *sizeof(int));
for (i = 0; i < count; i++) {
for (j = 0; j < count -1; j++) {
if (cmp(target[j], target[j + 1]) > 0) {
temp = target[j +1];
target[j +1] = target[j];
target[j] = temp;
}
}
}
printf("I:%d J:%d\n",i, j);
return target;
}
int sorted_order(int a, int b)
{
return a - b;
}
int reverse_order(int a, int b)
{
return b - a;
}
int strange_order(int a, int b)
{
if (a == 0 || b == 0) {
return 0;
}else {
return a % b;
}
}
/**
* Used to test that we are sorting things correctly
* by doing the sort and printging it out;
*/
void test_sorting(int *numbers, int count, compare_cb cmp)
{
int i = 0;
int *sorted = bubble_sort(numbers, count, cmp);
if (!sorted)
die("Failed to sort as requested.");
for ( i = 0; i < count; i++) {
printf("%d ", sorted[i]);
}
printf("\n");
free(sorted);
}
int main(int argc, char *argv[])
{
if (argc < 2) die("USAGE: ./ex18 4 3 1 5 6");
int count = argc - 1;//except ./ex18
int i = 0;
char **inputs = argv + 1;//cha 1
int *numbers = malloc(count *sizeof(int));
if (!numbers)
die("Memory error.");
for (i = 0; i < count; i++) {
numbers[i] = atoi(inputs[i]);
}
test_sorting(numbers, count, sorted_order);
test_sorting(numbers, count, reverse_order);
test_sorting(numbers, count, strange_order);
free(numbers);
return 0;
}
此段代码是不是定义了指针函数却没有声明函数原型,还是说有三个声明?难道不应该是定义好后就声明原型吗?