/*Write a program to implement STACK data structure. Stack works on the principle of LIFO (last in first out). For example: A stack of dishes. Here you can
add(push) a dish only at the top of the stack and can also remove(pop) a disk only from the top of the stack.
Implement an integer stack using an integer array.
You can do this by defining a class MyStack.
-Mystack will have an private integer array of size 10.

-MyStack will have an private integer variable TOP, which is initialized to -1 and will be incremented everytime an integer is pushed on the stack. Thus, TOP always
contains the index of the last element entered in the stack.

-Stack will define following 3 operations:
1) void push(int val): First, it checks if the stack(integer array) is full, if so it prints the message 'Stack is full' and returns.
Otherwise, it will increment TOP by 1 and store 'val' in the array at the position TOP. 
HINT: stack is full if TOP==9 
2) int pop(): First, it checks if the stack(integer array) is empty, if so it prints the message 'Stack is empty' and returns.
Otherwise, it will retrive the element indexed by TOP and then it will decrement TOP by 1.
HINT: stack is empty if TOP==-1
3) void print(): This will print all the elements of the stack. 
 
 Define one more 'class TestStack' having the main function. 
 Give options to user to: 
 1) push an element 
 2) pop an element 
 3) print stack(optional)
 4) Exit
 Get the choice from the user and depending on this choice perform the operations on the stack.
  
 
*/


import java.util.Scanner;

class  Teststack                               //class for testing stack operation
{
	public static void main(String[] args) 
	{
		int type_of_op;						  //variable used to store tupe of operation	
		Mystack ob1=new Mystack();            //created stack
		
		Scanner s = new Scanner(System.in);    

		while(true)
		{
			System.out.println("ente your choice");
			System.out.println("enter 1 for push a numer");
			System.out.println("enter 2 for pop a number");
			System.out.println("enter 3 for printing a stack elements");
			System.out.println("enter 4 for exit");
			type_of_op = s.nextInt();							//reading type value
			switch(type_of_op)
			{
			case 1: System.out.println("Enter your element which you want to push");
					//s.nextInt();
					ob1.push(s.nextInt());                   //reading integer and pushed it into the stack
					break;

			case 2: System.out.println("Element  you want to pop is "+ ob1.pop());
					break;

			case 3: System.out.println("stack element is ");
					ob1.print();
					break;
			default: System.out.println("You have entered the wrong choice"); 
					return ;

			}
		
		}
		
	}
}
class Mystack
{
	int st_elements[]=new int[10];
	int tos;
	Mystack()
	{
		tos = -1;        //indicate it's empty
	}

public void push(int item)  //for inserting element into stack in stack order
	{
	if(tos==10)                      
		{
		System.out.println("stack is full");
		return;
		}
		else
		{
		 st_elements[++tos] = item;
		}
	}
	public int pop()	//for retriving element from stack
	{
		if(tos<0)
		{
			System.out.println("stack underflow");
			return 0;
		}
		else
			return st_elements[tos--];
	}
	public boolean empty_stack() //check that stack is empty or not
	{
		if (tos == -1)
			return true;
		else return false;
	}
	public void print()		//for printing the stack contains
	{
		int temp=0;
		
		if(!empty_stack())
		{
			temp = pop();
			System.out.println(temp);
			print();
		}
		push(temp);
	}


};