Increment Value Pointer vs Reference

#include<iostream>
using namespace std;

int incrementPtr(int *x)
{
   return  ++(*x);
}

int incrementRef(int & x)
{
   return ++x;
}

int main()
{
   int n;
   cin>>n;

   int a = n;
   incrementPtr(&a);
   cout<<"After incrementPtr: "<<a<<endl;

   int b = n;
   incrementRef(b);
   cout<<"After incrementRef: "<<b<<endl;
}