Implementation of stack using linked list with code example

Basic idea behind on How to write a program for linked list implementation of stack.

Stack Program using Linked List concept

Steps

The Code push() function must be similar to the code of inserting the node at the beginning of singly linked list.

The Code pop() function must be similar to the code of deleting the first node of singly linked list.

check if memory available, stack overflow occurs, when there is no spack left to insert data. In that case malloc() function will return NULL.

Check if stack is empty while removing the item, stack underflow will occurs when stack is empty.

C Program to implement stack using linked List

// C++ program to Implement a stack
// using singly linked list
#include <bits/stdc++.h>
using namespace std;

// creating a linked list;
class Node {
public:
	int data;
	Node* link;

	// Constructor
	Node(int n)
	{
		this->data = n;
		this->link = NULL;
	}
};

class Stack {
	Node* top;

public:
	Stack() { top = NULL; }

	void push(int data)
	{

		// Create new node temp and allocate memory in heap
		Node* temp = new Node(data);

		// Check if stack (heap) is full.
		// Then inserting an element would
		// lead to stack overflow
		if (!temp) {
			cout << "\nStack Overflow";
			exit(1);
		}

		// Initialize data into temp data field
		temp->data = data;

		// Put top pointer reference into temp link
		temp->link = top;

		// Make temp as top of Stack
		top = temp;
	}

	// Utility function to check if
	// the stack is empty or not
	bool isEmpty()
	{
		// If top is NULL it means that
		// there are no elements are in stack
		return top == NULL;
	}

	// Utility function to return top element in a stack
	int peek()
	{
		// If stack is not empty , return the top element
		if (!isEmpty())
			return top->data;
		else
			exit(1);
	}

	// Function to remove
	// a key from given queue q
	void pop()
	{
		Node* temp;

		// Check for stack underflow
		if (top == NULL) {
			cout << "\nStack Underflow" << endl;
			exit(1);
		}
		else {

			// Assign top to temp
			temp = top;

			// Assign second node to top
			top = top->link;

			// This will automatically destroy
			// the link between first node and second node

			// Release memory of top node
			// i.e delete the node
			free(temp);
		}
	}

	// Function to print all the
	// elements of the stack
	void display()
	{
		Node* temp;

		// Check for stack underflow
		if (top == NULL) {
			cout << "\nStack Underflow";
			exit(1);
		}
		else {
			temp = top;
			while (temp != NULL) {

				// Print node data
				cout << temp->data;

				// Assign temp link to temp
				temp = temp->link;
				if (temp != NULL)
					cout << " -> ";
			}
		}
	}
};

// Driven Program
int main()
{
	// Creating a stack
	Stack s;

	// Push the elements of stack
	s.push(11);
	s.push(22);
	s.push(33);
	s.push(44);

	// Display stack elements
	s.display();

	// Print top element of stack
	cout << "\nTop element is " << s.peek() << endl;

	// Delete top elements of stack
	s.pop();
	s.pop();

	// Display stack elements
	s.display();

	// Print top element of stack
	cout << "\nTop element is " << s.peek() << endl;

	return 0;
}

Java Program to implement stack using linked list concept

// Java program to Implement a stack
// using singly linked list
// import package
import static java.lang.System.exit;

// Driver code
class GFG {
	public static void main(String[] args)
	{
		// create Object of Implementing class
		StackUsingLinkedlist obj
			= new StackUsingLinkedlist();
		// insert Stack value
		obj.push(11);
		obj.push(22);
		obj.push(33);
		obj.push(44);

		// print Stack elements
		obj.display();

		// print Top element of Stack
		System.out.printf("\nTop element is %d\n",
						obj.peek());

		// Delete top element of Stack
		obj.pop();
		obj.pop();

		// print Stack elements
		obj.display();

		// print Top element of Stack
		System.out.printf("\nTop element is %d\n",
						obj.peek());
	}
}

// Create Stack Using Linked list
class StackUsingLinkedlist {

	// A linked list node
	private class Node {

		int data; // integer data
		Node link; // reference variable Node type
	}
	// create global top reference variable global
	Node top;
	// Constructor
	StackUsingLinkedlist() { this.top = null; }

	// Utility function to add an element x in the stack
	public void push(int x) // insert at the beginning
	{
		// create new node temp and allocate memory
		Node temp = new Node();

		// check if stack (heap) is full. Then inserting an
		// element would lead to stack overflow
		if (temp == null) {
			System.out.print("\nHeap Overflow");
			return;
		}

		// initialize data into temp data field
		temp.data = x;

		// put top reference into temp link
		temp.link = top;

		// update top reference
		top = temp;
	}

	// Utility function to check if the stack is empty or
	// not
	public boolean isEmpty() { return top == null; }

	// Utility function to return top element in a stack
	public int peek()
	{
		// check for empty stack
		if (!isEmpty()) {
			return top.data;
		}
		else {
			System.out.println("Stack is empty");
			return -1;
		}
	}

	// Utility function to pop top element from the stack
	public void pop() // remove at the beginning
	{
		// check for stack underflow
		if (top == null) {
			System.out.print("\nStack Underflow");
			return;
		}

		// update the top pointer to point to the next node
		top = (top).link;
	}

	public void display()
	{
		// check for stack underflow
		if (top == null) {
			System.out.printf("\nStack Underflow");
			exit(1);
		}
		else {
			Node temp = top;
			while (temp != null) {

				// print node data
				System.out.print(temp.data);

				// assign temp link to temp
				temp = temp.link;
				if(temp != null)
					System.out.print(" -> ");
			}
		}
	}
}

Python Program on stack linked list

# python3 program to Implement a stack
# using singly linked list

class Node:

	# Class to create nodes of linked list
	# constructor initializes node automatically
	def __init__(self, data):
		self.data = data
		self.next = None


class Stack:

	# head is default NULL
	def __init__(self):
		self.head = None

	# Checks if stack is empty
	def isempty(self):
		if self.head == None:
			return True
		else:
			return False

	# Method to add data to the stack
	# adds to the start of the stack
	def push(self, data):

		if self.head == None:
			self.head = Node(data)

		else:
			newnode = Node(data)
			newnode.next = self.head
			self.head = newnode

	# Remove element that is the current head (start of the stack)
	def pop(self):

		if self.isempty():
			return None

		else:
			# Removes the head node and makes
			# the preceding one the new head
			poppednode = self.head
			self.head = self.head.next
			poppednode.next = None
			return poppednode.data

	# Returns the head node data
	def peek(self):

		if self.isempty():
			return None

		else:
			return self.head.data

	# Prints out the stack
	def display(self):

		iternode = self.head
		if self.isempty():
			print("Stack Underflow")

		else:

			while(iternode != None):

				print(iternode.data, end = "")
				iternode = iternode.next
				if(iternode != None):
					print(" -> ", end = "")
			return


# Driver code
if __name__ == "__main__":
MyStack = Stack()

MyStack.push(11)
MyStack.push(22)
MyStack.push(33)
MyStack.push(44)

# Display stack elements
MyStack.display()

# Print top element of stack
print("\nTop element is ", MyStack.peek())

# Delete top elements of stack
MyStack.pop()
MyStack.pop()

# Display stack elements
MyStack.display()

# Print top element of stack
print("\nTop element is ", MyStack.peek())

Javascript stack implementation linked list

// Javascript program to Implement a stack
// using singly linked list
// import package

// A linked list node
class Node
{
	constructor()
	{
		this.data=0;
		this.link=null;
	}
}

// Create Stack Using Linked list
class StackUsingLinkedlist
{
	constructor()
	{
		this.top=null;
	}
	
	// Utility function to add an element x in the stack
	push(x)
	{
		// create new node temp and allocate memory
		let temp = new Node();

		// check if stack (heap) is full. Then inserting an
		// element would lead to stack overflow
		if (temp == null) {
			document.write("<br>Heap Overflow");
			return;
		}

		// initialize data into temp data field
		temp.data = x;

		// put top reference into temp link
		temp.link = this.top;

		// update top reference
		this.top = temp;
	}
	
	// Utility function to check if the stack is empty or not
	isEmpty()
	{
		return this.top == null;
	}
	
	// Utility function to return top element in a stack
	peek()
	{
		// check for empty stack
		if (!this.isEmpty()) {
			return this.top.data;
		}
		else {
			document.write("Stack is empty<br>");
			return -1;
		}
	}
	
	// Utility function to pop top element from the stack
	pop() // remove at the beginning
	{
		// check for stack underflow
		if (this.top == null) {
			document.write("<br>Stack Underflow");
			return;
		}

		// update the top pointer to point to the next node
		this.top = this.top.link;
	}
	
	display()
	{
		// check for stack underflow
		if (this.top == null) {
			document.write("<br>Stack Underflow");
			
		}
		else {
			let temp = this.top;
			while (temp != null) {

				// print node data
				document.write(temp.data+"->");

				// assign temp link to temp
				temp = temp.link;
			}
		}
	}
}

// main class

// create Object of Implementing class
let obj = new StackUsingLinkedlist();
// insert Stack value
obj.push(11);
obj.push(22);
obj.push(33);
obj.push(44);

// print Stack elements
obj.display();

// print Top element of Stack
document.write("<br>Top element is ", obj.peek()+"<br>");

// Delete top element of Stack
obj.pop();
obj.pop();

// print Stack elements
obj.display();

// print Top element of Stack
document.write("<br>Top element is ", obj.peek()+"<br>");