Program With Array To Check For Increasing/Decreasing Numbers - c++

Question

Beginner C++ student here starting to learn different ways of using arrays. I am trying to put together the program below. It's supposed to ask the user for an input of a set of numbers that will go into an array. This set of numbers may increase or decrease at any point the user wants.
For example:
1 2 3 4 9 8 7 4 5 6 10 11 12 20 19 18 17
The program is to check against that set of numbers and account for every time there is an increase or decrease. Right now the program will return "increase" or "decrease".
For example, running it against the aforementioned set of numbers it returns:
increasing
decreasing
decreasing
However, I have two problems:
I think it is not accounting for all the changes (increases and decreases) occurring in the array correctly. Unsure where I have gone wrong.
I now have to return the number of changes that occur instead of "decrease"/"increase". Meaning, in the example above it would return "3" because there is 1 true value and 2 false.
If anyone can advise I would immensely appreciate the help.
Thank you so very much!!!
#include <iostream>
using namespace std;
bool increasing(int arr[], int n);
int main()
{
int arr[20], n;
cout << "Enter a set of Increasing/Decreasing numbers (ex. 1 2 3 6 5 4 7 8 9 3 2 1)." << endl;
cout << "Press 'Enter' to see results" << endl;
while (cin >> n)
{
for (int i = 0; i <= n; i++)
{
cin >> arr[i];
}
cout << (increasing(arr, n) ? "increasing" : "decreasing") << endl;
}
return 0;
}
bool increasing(int arr[], int n)
{
int x = 0;
for (int i = 0; i < n - 1; i++)
{
if (arr[i] < arr[i + 1])
{
x++;
}
}
if (x == n - 1)
{
return true;
}
else
{
return false;
}
}

Answer 1

For the needs of 1. you have to call the increasing function several times. So you also need an integer advance to remember your advance.
bool increasing(int arr[], int& advance, int n);
You can then call it with (x counts the number of increasing as stated in 2.)
int advance = 0;
do {
int x = 0;
cout << (increasing(arr, advance, n, x) ? "increasing " : "decreasing ") << x << endl;
} while (advance < n-1);
You can implement it with
bool increasing(int arr[], int& advance, int n, int& x)
{ assert(advance < n-1);
x = 0;
bool doesIncrease = arr[advance] < arr[advance + 1];
bool isStable = arr[advance] == arr[advance + 1];
if (doesIncrease) {
for (int i = advance+1; i < n - 1; i++)
{
if (arr[i] < arr[i + 1])
{
x++;
}
}
}
else if (isStable) {
...
}
else { // decreasing
for (int i = advance+1; i < n - 1; i++)
{
if (arr[i] > arr[i + 1])
{
x++;
}
}
};
return doesIncrease;
}