C program to Implement Stack and its operation | Push | pop

STACK :- A Stack is a data structure following the LIFO(Last In, First Out) principle If you have trouble visualizing stacks, just assume a stack of books. In a stack of books, you can only see the top book If you want to access any other book, you would first need to remove the books on top of it The bottom-most book in the stack was put first and can only be removed at the last after all books on top of it have been removed.
PUSH:- Push, which adds an element to the collection
POP :-Pop, which removes the most recently added element that was not yet removed.

 // write a program in to implement stack and its
 // PUSH and POP Operation
 #include <stdio.h>
 #include <conio.h>
 int main()
 {
	int top = -1, ch, size,m, s[20], i, j;
	printf("Enter size of stack:\n");
	scanf("%d", &size);
	do
	{
		printf("Choose one of these options \n");
		printf(" 1. Push\n");
		printf("2. Pop\n");
		printf("3. Display Element\n");
		printf("Enter your choice:\n");
		scanf("%d", &ch);
		if (ch == 1)
		{
			if (top == (size - 1))
			{
				printf("stack overflow\n");
			}
			else
			{
				printf("Enter element :\n");
				scanf("%d", &m);
				top = top + 1;
				s[top] = m;
			}
		}
		else if (ch == 2)
		{
			if (top == -1)
			{
				printf(" Stack Underflow\n");
			}
			else
			{
				int val = s[top];
				printf("Delete element is %d\n", val);
				top = top - 1;
			}
		}
		else if (ch == 3)
		{
			if (top == -1)
			{
				printf("Stack Empty:\n");
			}
			else
			{
					printf("\n\n Elements in stack: ", s[i]);
				for (i = 0; i <= top; i++)
				{
					printf("%d\t", s[i]);
				}
				printf("\n");
			}
		}
		else
		{
			printf("You have entered invalid option!");
		}
	} while (ch == 1 || ch == 2 || ch == 3);
	return 0;
 }

When the above program is executed, it produces following results --

  Enter size of stack:
  20
  Choose one of these options 
   1. Push
  2. Pop
  3. Display Element
  Enter your choice:
  1
  Enter element :
  23
  Choose one of these options 
   1. Push
  2. Pop
  3. Display Element
  Enter your choice:
  1
  Enter element :
  78
  Choose one of these options 
   1. Push
  2. Pop
  3. Display Element
  Enter your choice:
  3


   Elements in stack: 23  78
  Choose one of these options 
   1. Push
  2. Pop
  3. Display Element
  Enter your choice:
  2
  Delete element is 78
  Choose one of these options 
   1. Push
  2. Pop
  3. Display Element
  Enter your choice:
  3
  
  
   Elements in stack: 23
  Choose one of these options
   1. Push
  2. Pop
  3. Display Element
  Enter your choice: