// C++ program to Implement a stack

//using singly linked list

#include <bits/stdc++.h>

using namespace std;

// Declare linked list node

struct Node

{

    int data;

    struct Node* link;

};

struct Node* top;

// Utility function to add an element

// data in the stack insert at the beginning

void push(int data)

{

    // Create new node temp and allocate memory

    struct Node* temp;

    temp = new Node();

    // Check if stack (heap) is full.

    // Then inserting an element would

    // lead to stack overflow

    if (!temp)

    {

        cout << "\nHeap 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

int isEmpty()

{

    return top == NULL;

}

// Utility function to return top element in a stack

int peek()

{

    // Check for empty stack

    if (!isEmpty())

        return top->data;

    else

        exit(1);

}

// Utility function to pop top

// element from the stack

void pop()

{

    struct Node* temp;

    // Check for stack underflow

    if (top == NULL)

    {

        cout << "\nStack Underflow" << endl;

        exit(1);

    }

    else

    {

        // Top assign into temp

        temp = top;

        // Assign second node to top

        top = top->link;

        // Destroy connection between

        // first and second

        temp->link = NULL;

        // Release memory of top node

        free(temp);

    }

}

// Function to print all the

// elements of the stack

void display()

{

    struct 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;

        }

    }

}

// Driver Code

int main()

{

    // Push the elements of stack

    push(11);

    push(22);

    push(33);

    push(44);

    // Display stack elements

    display();

    // Print top element of stack

    cout << "\nTop element is "

         << peek() << endl;

    // Delete top elements of stack

    pop();

    pop();

    // Display stack elements

    display();

    // Print top element of stack

    cout << "\nTop element is "

         << peek() << endl;

    return 0;

}

// This code is contributed by Striver

//using PUSH, POP and DISPLAY functions

#include<stdio.h>

#include<stdlib.h>

​

struct node{

    int data;

    struct node* next;

};

struct node* top=NULL;

​

void push(){

    struct node* neww= (struct node*)malloc(sizeof(struct node));

    scanf("%d",&neww->data);

    neww->next=top;

    top=neww;

    printf("Node is Inserted\n");

}

​

void pop(){

    struct node* temp=top;

    if(top==NULL){

        printf("EMPTY STACK");

    }

    else{

    printf("Popped Element : %d\n",temp->data);

    top=top->next;

    free(temp);

    }

}

​

void display(){

    if(top!=NULL){

        printf("The stack is \n");

        while(top!=NULL){

            printf("%d ",top->data);

            top=top->next;

        }

    }

    else{

        printf("EMPTY STACK");

    }

}

​

int main(){

    int n;

    while(true){

    scanf("%d",&n);

    switch(n){

        case 1:

        push();

        break;

        case 2:

        pop();

        break;

        case 3:

        display();

        break;

        case 4:

        exit(0);

        default:

        printf("Wrong choice");

    }

    }

    return 0;

}

​

//INPUT:

1

10

1

20

1

30

1

40

1

50

2

2

3

4

//OUTPUT:

Node is Inserted

Node is Inserted

Node is Inserted

Node is Inserted

Node is Inserted

Popped Element : 50

Popped Element : 40

The stack is 

30 20 10 

#include<iostream>

using namespace std;

class node{

    public:

        int data;

        node* next;

        void push();

        void pop();

        void display();

};

node *top=NULL;

void node::push()

{

    node* newnode;

    newnode=new node();

    cout<<"Enter data : ";

    cin>>newnode->data;

    newnode->next=top;

    top=newnode;

}

void node::pop()

{

    if(top==NULL)

    {

        cout<<"Stack underflow!";

    }

    else

    {

        cout<<"poped element is : "<<top->data;

        top=top->next;

    }

}

​

void node::display()

{

    node *temp=top;

    if(temp==NULL)

    {

        cout<<"\nThe Stack is Empty!\n";

    }

    else

    {

    while(temp!=NULL)

    {

        cout<<temp->data<<" ";

        temp=temp->next;

    }

    }

}

int main()

{

    node obj;

 int ch;

    while(ch!=4){

        cout<<"\n1) Push in stack"<<endl;

        cout<<"2) Pop from stack"<<endl;

        cout<<"3) Display stack"<<endl;

        cout<<"4) Exit"<<endl;

        cout<<"Enter choice: "<<endl;

      cin>>ch;

      switch(ch) {

         case 1: {

            obj.push();

            break;

         }

         case 2: {

            obj.pop();

            break;

         }

         case 3: {

            obj.display();

            break;

         }

         case 4: {

            exit(0);

            break;

         }

         default: {

            cout<<"Invalid Choice"<<endl;

         }

}

}

}

​

​

​

#include<iostream>

using namespace std;

​

struct stackNode {

  int data;

  stackNode * next;

  int size;

  stackNode(int d) {

    data = d;

    next = NULL;

  }

};

struct stack {

  stackNode * top;

  int size;

  stack() {

    top = NULL;

    size = 0;

  }

  void stackPush(int x) {

    stackNode * element = new stackNode(x);

    element -> next = top;

    top = element;

    cout << "Element pushed" << "\n";

    size++;

  }

  int stackPop() {

    if (top == NULL) {

      return -1;

    }

    int topData = top -> data;

    stackNode * temp = top;

    top = top -> next;

    delete temp;

    size--;

    return topData;

  }

  int stackSize() {

    return size;

  }

  bool stackIsEmpty() {

    return top == NULL;

  }

  int stackPeek() {

    if (top == NULL) return -1;

    return top -> data;

  }

  void printStack() {

    stackNode * current = top;

    while (current != NULL) {

      cout << current -> data << " ";

      current = current -> next;

    }

  }

};

int main() {

  stack s;

  s.stackPush(10);

  cout << "Element popped: " << s.stackPop() << "\n";

  cout << "Stack size: " << s.stackSize() << "\n";

  cout <<"Stack empty or not? "<<s.stackIsEmpty()<<"\n";

  cout << "stack's top element: " << s.stackPeek() << "\n";

  return 0;

}