How to print an array in descending order? - c++

Question

Basically this is my code and it works fine. I just don't know how to print it in descending order. This code basically shows the odd numbers:1,3,5,7. I want it to be printed 7,5,3,1. I know I need use the sort function but I dont know how.
#include <iostream>
using namespace std;
void fillArray(int arr[], int &n);
void printArray(int arr[], int n);
void findSum(int arr[], int &n);
int main()
{
int n;
cin>>n;
int arr[n];
fillArray(arr,n);
printArray(arr,n);
findSum(arr,n);
return 0;
}
void fillArray(int arr[], int &n)
{
int j=1;
for(int i=0;i<n;i++)
{
if(j%2==1)
arr[i]=j;
else
i--;
j++;
}
}
void printArray(int arr[], int n)
{
for(int i=0;i<n;i++)
{
cout<<arr[i]<<", ";
}
}
void findSum(int arr[], int &n)
{
int sum=0;
for(int i=0;i<n;i++)
{
sum=sum+arr[i];
}
}

Answer 1

for(int i = n-1; i >= 0; i--)
{
cout << arr[i] << ", ";
}

Answer 2

example:
void printArray(int *tab, int size)
{
for (int i = size - 1; i >= 0; i--)
std::cout << tab[i] << std::endl;
}
int main() {
int tab[3] = { 1,2,3 };
printArray(tab, 3);
}
You should begin from last element array, and decrement iterator (i) to i == 0

Answer 3

You can simply use a sort function. There is one included with the algorithm header.
#include <algorithm> // this goes at the top
void printArray(int arr[], int n)
{
sort(arr, arr+n, [](int x, int y){return y<x;});
for(int i=0;i<n;i++)
cout << arr[i] << endl;
}
the [](int x, int y){return y<x;} part is just to make it descending. Normally it is y>x, at which point you can just omit the third parameter
Here is a repl:
https://repl.it/JQor/0