how to check whether a stack is empty or full in c code example

Example 1: sum of stack c++

stack<int> si;
    int sum = 0;
    stack<int> tsi(si);
    while (!tsi.empty()) {
        sum += tsi.top();
        tsi.pop();
    }

Example 2: check an stack is empty c++

std::stack <int> st;
if(st.empty())
  std::cout << "stack is empty";