Navigation Demo

STACK

Stack is an ordered collection of items and in c/c++ : array
Stack is an abstract data type which has it's own restrictions
Stack follows the concept of last in fist out(LIFO).
Stack has its own capacity i.e stack never has capacity of infinity. When we apply the rules of stack on Array it's comes out to be THE STACK.
Insetting and deleting of data from stack(Array) is only from one end called STACK TOP and stack is a dynamic, constantly changing object.

Operations on Stack

Push:
- When a data or item is added to the stack.
- Always creates a memory address then perform Push operation.
Pop:
- When a data or item is removed form the stack.
- Always removes the memory address and then perform Pop operation.
Stack Top:
- It is the data which currently pointed by stack pointer.
- Stack pointer strore the memory address/structure of the LAST IN data.
Stack Underflow:
- It is a property / statue / error for an empty stack.
- It's is an error as stack pointer can not access item form empty stack.
- If programmer initialized pointer to -1 by default, stack pointer will be -1 when stack is empty.
Stack Overflow:

It is a statue / result of push operation when stack is full.
Pointer value will be equal to the capacity of the stack

Stack Empty : Stack is in underflow condition.
Stack Full : Stack is in overflow condition.

Difference between Stack And Array

Stack:

Only one input
Fundamentally a dynamic object; whose size is constantly changing as items are popped and pushed.

Array:

Input can be multiple
Size of the array is fixed and user can not change to size

C++ code for Stair case

#include 
using namespace std;

int main() {
	int n;
	cout<<"Enter a number :";
	cin>>n;
	int k=1;
	for (int i=n; i >0; i--){

		for( int j=n-1; j>0; j--){
			cout<<" ";
		}
		for(int z=k; z>0; z--){
		cout<<"#";
		}
		k++;
		n--;
		cout<
                    
------ OUT PUT--------
Enter a number :6
     #
    ##
   ###
  ####
 #####
######