Stack and its operations

Introduction to Data Structure

• We can use data structure depending upon our areas of application.
• A data structure can be simple or complex.
• These kinds of data structures are known as Fundamentals data structure or Classic data structure.
  
• There are two kinds of classic data structure.

1. Linear.
2. Non-Linear.

• The Linear data structure can be categories as:

1. Array
2. Linked List
3. Queue
4. Stack

• The non-linear data structure can be categories as:

1. Files
2. Tables
3. Tree
4. Graph

 

Stacks

• Stack is a linear data structure.
  
• It is very useful for various applications for computer science.
  
• Example: Shunting train in railway yards
• Example: Shipment in cargo 
• Example: Plates on a tray
• Example: Stacks of coins
• Example: Stacks of drawers
• The strategy to store and retrieve in stack data structure is LIFO.
• LIFO stands for Last In First Out.
• The stack data structure has the following kinds of characteristics:
• It is an ordered collection.
• It has homogeneous data elements.
• It can insert or delete elements.
• The insertion and deletion take place at one end only
• The insertion operation in stack called a PUSH.
• The deletion operation in stack called a POP. 
  

• The PUSH & POP operations performed on the position of the stack are called TOP of the stack.
• The elements of the stack are called an ITEM.
• The maximum number of elements is considering as SIZE.
• Sometimes, a stack may face two different kinds of errors.
• Underflow: when POP operations performed and stack is empty.
  

SIZE = 5 and POP operations

• Overflow: when PUSH operation performed and stack is a full.
  

SIZE = 5 & PUSH operations

Representation of STACK

• You can implement STACK using any computer programming language.
• We can implement STACK using various ways:
• Using One Dimension array
  
• Using Single Linked List
  

Operations on STACK

• The basic operations on STACK are:
• Push: It is used to insert a new item.
  
• Pop: It is used to delete existing item
  
• Peep or Peek: It is used to pick up existing items.
  
• Change: It is used to change the existing items.