Stack is a linear data structure that follows LIFO (Last In First Out) order. Elements can only be added or removed from one end called the top. There are four main operations on a stack: creation, insertion (push), deletion (pop), and displaying. Pushing adds an element to the top of the stack. Popping removes and returns the top element. The document provides examples of implementing these stack operations in C code using an array to represent the stack.

1. STACK
NAME – RUPAM TARAFDAR

2. WHAT IS A STACK?
 It is named stack as it behaves live a real-world like stack
 Stack is a linear data structure which follows a particular orderwhich the
operations are performed. The order may be LIFO(Last In First Out) .
 Stack is a sequence of items that can be accessed at only one end of the
sequence known as top.

3. REAL LIFE EXAMPLES OF STACK

4. WHAT IS A STACK?

5. OPERATIONS ON STACK
CREATION
INSERTION
DELETION
DISPLAYING

6. CREATION
#define MAX 5
int stack[MAX];
int Top = -1;

7. INSERTION
 Before inserting an element in a stack, we check whether the stack is full.
 If we try to insert the element in a stack, and the stack is full, then the overflow condition occurs.
 When we initialize a stack, we set the value of top as -1 to check that the stack is empty.
 When the new element is pushed in a stack, first, the value of the top gets incremented, i.e., top=top+1,
and the element will be placed at the new position of the top.
 The elements will be inserted until we reach the max size of the stack.

8. STACK EXAMPLES : PUSH
Insertion operation in stack called "Push"
void Push()
{
int x;
if(Top==Size-1)
{
printf("nOverflow!!");
}
else
{
printf("nEnter element to be inserted to the stack:");
scanf("%d",&x);
Top=Top+1;
inp_array[Top]=x;
}
}

9. STACK : PUSH OPERATION EXAMPLE

10. DELETION
 Before deleting the element from the stack, we check whether the stack is empty.
 If we try to delete the element from the empty stack, then the underflow condition occurs.
 If the stack is not empty, we first access the element which is pointed by the top
 Once the pop operation is performed, the top is decremented by 1, i.e., top=top-1.

11. STACK EXAMPLES : POP
Deletion operation is called as "Pop"
void Pop()
{
if(Top==-1)
{
printf("nUnderflow!!");
}
else
{
printf("nPopped element: %d",inp_array[Top]);
Top=Top-1;
}
}

12. STACK : POP OPERATION EXAMPLE

13. STACK EXAMPLES : DISPLAY
void display()
{
if(Top==-1)
{
printf("nUnderflow!!");
}
else
{
printf("nElements present in the stack: n");
for(int i=Top;i>=0;--i)
printf("%dn",inp_array[i]);
}
}