ex18.c

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>

void die(const char* message)
{
	if(errno) {
		perror(message);}
	else {
		printf("ERROR: %s\n",message);}
	exit(1);
}

typedef int (*compare_cb)(int a, int b);

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;}}}

	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;} 
}

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");}

	int i     = 0;
	int count = argc - 1;
	char** inputs = argv + 1;

	int* numbers = malloc(count*sizeof(int));
	if(!numbers) {
		die("Memmory 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;
}