AB said:
what I
needed help on was passing the parameters to the comparison function.
That's what I posted.
You had this line:
if(cmp((int *) &arr[j-1], (int *) &arr[j]))
Compare that to this line:
if (compar(arr + j * size, arr + (j + 1) * size) > 0) {
For one thing,
you have no relational operator in your comparison line.
It swaps elements whenever they are unequal.
The other problem, is that in your posted code
you have
void *arr
which means that you can't have
arr[j]
I order to be able to write that, and make it have meaning
the declaration of arr would have to be
int *arr
which means that you function would only be able to arrays
of type int.
Notice that your function doesn't use the size parameter.
This would work,
if you only ever used it with arrays of type int:
void sort(void *base, size_t num, size_t size,
int (*cmp)(const void *a, const void *b))
{
int i = 0 ;
int j = 0 ;
int *arr = base;
for (i = (num - 1) ; i >= 0 ; i--)
{
for (j = 1 ; j <= i ; j++)
{
if(cmp((int *) &arr[j-1], (int *) &arr[j]) > 0)
{
/* swapping logic */
}
}
}
}
However, since a sort that only sorts arrays of type int
isn't your assignment, it should be more like this:
void sort(void *base, size_t nmemb, size_t size,
int (*compar)(const void *, const void *))
{
unsigned char *arr = base;
size_t i = nmemb ;
size_t j ;
while (i-- > 0) {
for (j = 0 ; i > j ; ++j) {
if (compar(arr + j * size, arr + (j + 1) * size) > 0) {
/* swapping logic */
}
}
}
}
Try not to be distracted by the difference in the loops.
That's not your code anymore, that's my code;
that's why it looks like that.
I tested it before I posted it the first time.
The original order of the array is:
4.000000 3.500000 1.000000 2.000000
The sorted order of the array is:
1.000000 2.000000 3.500000 4.000000
/* BEGIN new.c */
#include <stdio.h>
#define E_TYPE double
#define BYTE_SWAP(A, B) \
{ \
p1 = (A); \
p2 = (B); \
end = p2 + size; \
do { \
swap = *p1; \
*p1++ = *p2; \
*p2++ = swap; \
} while (p2 != end); \
}
typedef E_TYPE e_type;
int comparison(const void *arg1, const void *arg2);
void sort(void *base, size_t nmemb, size_t size,
int (*compar)(const void *, const void *));
int main(void)
{
e_type array[] = {(4), (3.5), (1), (2)};
size_t x;
puts("The original order of the array is:");
for (x = 0; x != sizeof array / sizeof *array; ++x) {
printf("%f ", array[x]);
}
puts("\n");
sort(array, sizeof array / sizeof *array,
sizeof *array, comparison);
puts("The sorted order of the array is:");
for (x = 0; x != sizeof array / sizeof *array; ++x) {
printf("%f ", array[x]);
}
putchar('\n');
return 0;
}
int comparison(const void *arg1, const void *arg2)
{
return *(e_type*)arg2 > *(e_type*)arg1 ? -1
: *(e_type*)arg2 != *(e_type*)arg1;
}
void sort(void *base, size_t nmemb, size_t size,
int (*compar)(const void *a, const void *b))
{
unsigned char *arr = base;
size_t i = nmemb ;
size_t j ;
unsigned char *p1, *p2, *end, swap;
while (i-- > 0) {
for (j = 0 ; i > j ; ++j) {
if (compar(arr + j * size, arr + (j + 1) * size) > 0) {
BYTE_SWAP(arr + j * size, arr + (j + 1) * size);
}
}
}
}
/* END new.c */
