Can't figure out why my Print Array is replacing elements - c++

Question

I'm taking a C++ class and we've gotten to pointers. The assignment we've been given is to basically bubble sort an array that was read from a text file by passing pointers as parameters for various functions. I think I have a decent setup that outputs what I'm looking for, but for specific actions, I'm getting a zero as an element when there isn't one written to the array.
#include <iostream>
#include <fstream>
using namespace std;
int capacity;
int count;
int readData(int *&arr);
void swap(int *xp, int *yp);
void bsort(int *arr, int last);
void writeToConsole(int *arr, int last);
void bubble_sort(int *arr, int last, int(*ptr)(int, int));
int ascending(int a, int b);
int descending(int a, int b);
int main() {
int *whatever = NULL;
count = readData(whatever);
cout << "Raw array data:" << endl;
writeToConsole(whatever, capacity);
cout << "After simple bubble sort:" << endl;
bubble_sort(whatever, capacity, ascending);
writeToConsole(whatever, capacity);
cout << "Now descending:" << endl;
bubble_sort(whatever, capacity, descending);
writeToConsole(whatever, capacity);
return 0;
}
int readData(int *&arr) {
ifstream inputFile;
inputFile.open("data.txt");
if (!inputFile) {
cout << "Error!";
}
inputFile >> capacity;
arr = new int[capacity];
for(int i = 0; i < capacity; i++){
inputFile >> arr[i];
}
inputFile.close();
return capacity;
}
void swap(int *xp, int *yp) {
int temp = *xp;
*xp = *yp;
*yp = temp;
}
void bsort(int *arr, int last) {
int i, j;
bool swapped;
for (i = 0; i < last + 1; i++)
{
swapped = false;
for (j = 0; j < last-i; j++)
{
if (arr[j] > arr[j+1])
{
swap(arr[j], arr[j+1]);
swapped = true;
}
}
// IF no two elements were swapped by inner loop, then break
if (swapped == false)
break;
}
}
void writeToConsole(int *arr, int last) {
cout << "[ ";
for(int i = 0; i < last; i++){
cout << arr[i] << " ";
}
cout << "]" << endl;
}
void bubble_sort(int *arr, int last, int(*ptr)(int, int)){
int i, j;
bool swapped;
for (i = 0; i < last; i++)
{
swapped = false;
for (j = 0; j < last-i; j++)
{
//Use the function pointer to determine which logic to use
if (ptr(arr[j] , arr[j+1]))
{
swap(arr[j], arr[j+1]);
swapped = true;
}
}
// IF no two elements were swapped by inner loop, then break
if (swapped == false)
break;
}
}
int ascending(int a, int b){
return a > b;
}
int descending(int a, int b){
return a < b;
}
My output looks like this:
Raw array data:
[ 8 4 7 2 9 5 6 1 3 ]
After simple bubble sort:
[ 0 1 2 3 4 5 6 7 8 ]
Now descending:
[ 9 8 7 6 5 4 3 2 1 ]
Any ideas as to why my second sort is throwing in a zero? Thank you!

Answer 1

you have to do this change is in bubble_sort function
for (j = 1; j < last - i; j++)
{
//Use the function pointer to determine which logic to use
if (ptr(arr[j-1], arr[j]))
{
swap(arr[j-1], arr[j]);
swapped = true;
}
}