how to obtain the last element of a stack in c++ code example

Example 1: find last element of an array c++

int arr={1,2,3,4,5,6};
int length=sizeof(arr)/sizeof(int);
int lastElement=aar[length-1];

Example 2: how to get last element of set in c++

set<int> s = {1,2,3}
auto it = s.end();
it--;
cout<<*it<<"\n"; // This refers to last element of a set