STACK POP - is used to remove the topmost element
(the most recently added one) from the stack.
INTRODUCTION
• Key Characteristics of pop: Removes
you actually know all about stacks because
the Top Element: Only the element at
you use a stack when playing cards, making
the top of the stack can be removed
pancakes, and storing laundry. A stack is the
using the pop operation.
way you group things together by placing one
• Updates the Stack: After the pop
thing on top of another and then removing
operation, the next element in the
things one at a time from the top of the stack.
stack becomes the new top.
It is amazing that something this simple is a
critical component of nearly every program • Error Handling: If the stack is empty,
that is written. In this chapter, you’ll learn a pop operation typically results in an
how to create and use a stack in your underflow error.
programs.
A STACK- When you hear the term “stack” SIZE - The size of a stack refers to the number
used outside the context of computer of elements currently stored in it. It is an
programming, you might envision a stack of important operation used to determine the
dishes on your kitchen counter. This current state of the stack.
organization is structured in a particular way: TOP - The top operation in a stack data
the newest dish is on top and the oldest is on structure is used to retrieve the value of the
the bottom of the stack. The only way to element currently at the top of the stack
access each dish is from the top of the stack. If without removing it. This operation is
you want the third dish (the third oldest on essential for accessing the most recently added
the stack), then you must remove the first two element, which aligns with the Last In, First
dishes from the top of the stack. Out (LIFO) principle.
A STACK- This place the third dish at the top EMPTY - The empty operation in a stack
of the stack making it available to be removed. data structure checks whether the stack
There’s no way to access a dish unless the contains any elements. It is a simple but
dish is at the top of the stack. You might be crucial operation used in many stack-based
thinking stacks are inefficient, and you’d be algorithms and scenarios.
correct if the objective was to randomly access
things on the stack. There are other data POP - Popping is the reverse process of
structures that are ideal for random access. pushing: it removes an item from the stack. It
However, if the object is to access things in is important to understand that popping an
the order in which they were placed on the item off the stack doesn’t copy the item. Once
stack, such as computer instructions, stacks an item is popped from the stack, the item is
are efficient. In these situations, using a stack no longer available on the stack, although the
makes a lot of sense. value remains in the array.
PUSH - Programmers use the term “push” to
mean placing an item on a stack. Push is the
direction that data is being added to the stack.
Think of this as pushing items down on the
stack to move the items already on the stack
down to make room for the next item.
