<stack> is a LIFO container adapter: you push on the top and pop from the top. It's built on top of a deque or vector and exposes only stack semantics.

Use it when you need a simple LIFO data structure; otherwise use a vector directly.

This example demonstrates push, pop, and top operations on a LIFO stack, showing last-in-first-out ordering.

// compile: g++ -std=c++11 -o stackexample stackexample.cpp
// run: ./stackexample
// description: LIFO stack operations
 
#include <stack>
#include <iostream>
 
int main() {
    std::stack<int> st;
    st.push(1);
    st.push(2);
    st.push(3);
 
    std::cout << "top: " << st.top() << "\n";
    st.pop();
    std::cout << "after pop, top: " << st.top() << "\n";
 
    std::cout << "size: " << st.size() << "\n";
 
    return 0;
}