The std::stack class is a container adapter that gives the programmer the functionality of a stack - specifically, a FILO (first-in, last-out) data structure.

The class template acts as a wrapper to the underlying container - only a specific set of functions is provided. The stack pushes and pops the element from the back of the underlying container, known as the top of the stack.

A small demo program of stack

#include <iostream>
#include <stack>

using namespace std;

int main()
{
    stack <int> s; //declaring a stack variable which will hold integer values
    for (int i = 0; i < 10; i++) {
        s.push(i); //pushing element inside the stack
    }

    while (!s.empty()) {
        cout << "Element at the top : ";
        cout << s.top();
        cout << " size of stack ";
        cout << s.size() << endl;
        s.pop(); //remove the last element from the stack
    }

    return 0;
}

Output of the above program will be :

Element at the top : 9 size of stack 10
Element at the top : 8 size of stack 9
Element at the top : 7 size of stack 8
Element at the top : 6 size of stack 7
Element at the top : 5 size of stack 6
Element at the top : 4 size of stack 5
Element at the top : 3 size of stack 4
Element at the top : 2 size of stack 3
Element at the top : 1 size of stack 2
Element at the top : 0 size of stack 1

Member functions of Stack are given below

Element access
top

Capacity
empty
size

Modifiers
push
pop
emplace
swap

Some applications of Stack

1. Expression Evolution
2. Expression conversion
• Infix to Postfix
• Infix to Prefix
• Postfix to Infix
• Prefix to Infix
3. Parsing
4. Simulation of recursion
5. Fuction call