STL STACK

STL STACK

• Stacks are a type of container adaptors.
• Operate in a LIFO context (last-in first-out), where elements are inserted and extracted only from the end of the container.
• Stacks are implemented as containers adaptors, which are classes that use an encapsulated object of a specific container class as its underlying container, providing a specific set of member functions to access its elements. Elements are pushed/popped from the "back" of the specific container, which is known as the top of the stack.
• The underlying container may be any of the standard container class templates or some other specifically designed container class. The only requirement is that it supports the following operations:

1. back()
2. push_back()
3. pop_back()

• Therefore, the standard container class templates vector, deque and list can be used. By default, if no container class is specified for a particular stack class, the standard container class template deque is used.

EXAMPLE

// stack::top
# include < iostream >
# include < stack >
using namespace std;

int main ()
{
  stack< int > mystack;

  mystack.push(10);
  mystack.push(20);

  mystack.top() -= 5;

  cout << "mystack.top() is now " << mystack.top() << endl;

  return 0;
}

Output:

mystack.top() is now 15