Question

can some help me why it is erroring. I cannot find the mistake in the code. It is to implment a circular double linked list. please and thank you

//////////////////////////////////////////////////////////////////////////

HEADER FILE

////////////////////////////////////////////////////////////////////////

#pragma once
#include <cstdlib>



template <typename T>

class Node
{
public:
   T val;
   Node<T> *next;
   Node(T v)
   {
       val = v;
       next = NULL;
   }
};

///////////////////////////////////////////////////////////////////////////////////

STACK.CPP FILE

///////////////////////////////////////////////////////////////////////////////////

#include "Stack.h"

template <typename T>

class Stack
{
private:
   //head of the stack
   Node<T> *stack;
   // size or number of the values within the stack
   int size;
public:
   Stack()
   {
       size = 0;
   }
   //push function
   void push(T val);
   {
       // create a node of type Node<T> pointer
       Node<T> *node = new Node<T>(val);
       if (stack == NULL)
       {
           stack = node;
       }
       else
       {
           //if not linked to the current node to the stack
           //and make the head of stack as node
           node->next = stack;
           stack = node;
       }
       size++;
   }
   T pop()
   {
       //iif stack is empty return null
       if (isEmpty())
       {
           return NULL;
       }
       else
       {
           //if it isnt set the head of the stack to the next node , then store
           // the head node value to return
           T del = stack->val;
           stack = stack->next;
           size--;
           return del;
       }
   }
   bool isEmpty()
   {
       return size == 0 ? true : false;
   }
};

////////////////////////////////////////////////////////////////////////////

/DRIVER FILE....................

////////////////////////////////////////////////////////////////////////////

#include <fstream>
#include <iostream>
#include "Stack.h"

using namespace std;

int main()
{
   Stack<string> stack;
   string fileName = "input.txt";
   ifstream input(fileName.c_str());
   if (input == 0)
   {
       cout << "\nError: inp.txt is not found";
       return 0;
   }

   string line;
   cout << "pushing following lines from inp.txt into Stack\n\n";
   while (getline(inp, line))
   {
       cout << line << endl;
       Stack.push(line);
   }
   inp.close();

   ofstream out("out.txt");
   string top = " ";
   cout << " \n Writing following lines to out.txt \n\n";
   while (!stack.isEmpty())
   {
       //pop a value from stack and write it to file
       top = stack.pop();
       cout << top << " \n";
   }
   out.close();
   return 0;
}

/////////////////////////////////////////////

INPUT FILE

/////////////////////////////////

//input.txt -----------

1 2 3 4 5 6 7 8
one two
three four five
six seven eight nine

//output.txt -----------

six seven eight nine
three four five
one two
1 2 3 4 5 6 7 8

Answer 1

C++ PROGRAM

(Stack.h )File

#include <cstdlib>

// Create template class Node
template <typename T>
class Node
{
public:
   // Node members
T val;
Node<T> *next;
Node(T v) // create constructor for Node
{
val = v;
next = NULL;
}
};

(MyStack.h) File

#include "Stack.h"

template <typename T>

class Stack
{
private:
//head of the stack
Node<T> *stack;
// size or number of the values within the stack
int size;
public:
Stack()
{
size = 0;
}
//push function
void push(T val)
{
// create a node of type Node<T> pointer
Node<T> *node = new Node<T>(val);
if (stack == NULL)
{
stack = node;
}
else
{
//if not linked to the current node to the stack
//and make the head of stack as node
node->next = stack;
stack = node;
}
size++;
}
T pop()
{
//iif stack is empty return null
if (isEmpty())
{
return NULL;
}
else
{
//if it isnt set the head of the stack to the next node , then store
// the head node value to return
T del = stack->val;
stack = stack->next;
size--;
return del;
}
}
bool isEmpty()
{
return size == 0 ? true : false;
}
};

(driver.cpp) File

#include <fstream>
#include <iostream>
#include "MyStack.h" // You should include MyStack.h header file (You declare only Stack.h header file)

using namespace std;

int main()
{
Stack<string> stack;
string fileName = "d:\\Myinput1.txt"; // declare file name in specific path
ifstream input(fileName.c_str());
if (input == 0)
{
cout << "\nError: inp.txt is not found";
return 0;
}

string line;
cout << "pushing following lines from inp.txt into Stack\n\n";
while (getline(input, line)) // in getline() function using input(input file object ie "input") you declare "inp"
{
cout << line << endl;
stack.push(line); // call Stack object "stack" you declare "Stack"
}
input.close();

ofstream out("d:\\Myout1.txt"); // declare file name in specific path
string top = " ";
cout << " \n Writing following lines to out.txt \n\n";
while (!stack.isEmpty())
{
//pop a value from stack and write it to file
top = stack.pop();
cout << top << " \n";
}
out.close();
return 0;
}

OUTPUT

pushing following lines from inp.txt into Stack

1 2 3 4 5 6 7 8
one two
three four five
six seven eight nine

Writing following lines to out.txt

six seven eight nine
three four five
one two
1 2 3 4 5 6 7 8