Data Structures Program on Stack using Linked list

  #include< iostream >
  #include< cstdlib >
  #include< malloc.h >
  #include< conio.h >
  using namespace std;
  struct node
  {
     int info;
     struct node *next;
  };
  class stack
  {
     struct node *top;
     public:
       stack();
       void push();
       void pop();
        void display();
  };
  stack::stack()
  {
     top = NULL;
  }
  void stack::push()
  {
     int data;
     struct node *p;
     if((p=(node*)malloc(sizeof(node)))==NULL)
     {
       cout<<"Memory Exhausted";
       exit(0);
     }
     cout<<"Enter a Number to insert:";
     cin>>data;
     p = new node;
     p->info = data;
     p->next = NULL;
     if(top!=NULL)
     {
       p->next = top;
     }
     top = p;
     cout<<"\nNew item inserted"<< endl;
  }
  void stack::pop()
  {
     struct node *temp;
     if(top==NULL)
     {
       cout<<"\nThe stack is Empty"<< endl;
     }
     else
     {
       temp = top;
       top = top->next;
       cout<<"\nThe value popped is "<< temp->info<< endl;
       delete temp;
     }
  }
  void stack::display()
  {
     struct node *p = top;
     if(top==NULL)
     {
       cout<<"\nNothing to Display\n";
     }
     else
     {
       cout<<"\nThe contents of Stack\n";
       while(p!=NULL)
       {
         cout<< p->info<< endl;
         p = p->next;
       }
     }
  }
  int main()
  {
     stack s;
     int choice;
     do
     {
       cout<<"\nEnter your choice:";
       cout<<"\n1. PUSH\n2. POP\n3. DISPLAY\n4. EXIT\n";
       cin>>choice;
       switch(choice)
       {
         case 1:
           s.push();
           break;
         case 2:
           s.pop();
           break;
         case 3:
           s.display();
           break;
         case 4:
           exit(0);
           break;
         default:
           cout<<"Invalid Choice";
           break;
       }
     }while(choice);
     getch();
     return 0;
  }