The document discusses stacks and their operations. A stack is a data structure that uses LIFO (Last In First Out) methodology to store and retrieve objects. Items are added to the top of the stack using a push operation and removed from the top using a pop operation. The top of the stack is dynamically determined as items are pushed on and popped off. Stacks can be implemented using static arrays that allocate fixed block of memory.

1. Stack Operation
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2. Insertion in Stack
 When an object is added to a stack, it is placed on the top of all previously
entered items.
 When an item is removed, it can either be removed from the top.
 LIFO (Last in First Out ) method is used in stack operation.

3. What is Stack?
 Stack is data structure used to store a collection of objects.
 Individual items can be added and stored in a stack using a push operation.
 Objects can be retrieved using a pop operation, which removes an item from the
stack.

4. How?
Top
Bottom
Push
Pop

5. Static Memory allocation
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Int stack[6]
0
1
2
3
4
5
-1

6. Stack Operation
 Top: Open end of the stack is called Top, From this end item can be inserted.
 Push: To insert an item from Top of stack is called push operation. The push
operation change the position of Top in stack.
 POP: To put-off, get or remove some item from top of the stack is the pop
operation, We can POP only from top of the stack.
 IsEmpty: Stack considered empty when there is no item on Top. IsEmpty operation
return true when no item in stack else false
 IsFull: Stack considered full if no other element can be inserted on top of the
stack. This condition normally occur when stack implement ed through array.

7. Stack example
Empty
Stack 5 5 5
7
8
7
7
5 5
6
5
Push 5 Push 7 Push 8
Pop 8 Pop 7 Push 6 Pop 6
Pop 5
Empty
Stack

8. Implementation of Stack using Array.