how to reverse a stack

Question

I have an assignment where I am suppose to take a single stack, show the output and then reverse it to show the output.

Its suppose to look like this

Stack:
262 115 74 26 34 243 22 734 113 121
Stack Reversed:
121 113 734 22 243 34 26 74 115 262

Instead mine is coming out like this

Stack:
262 115 74 26 34 243 22 734 113 121 121 113 734 22 243 34 26 74 115 262
Stack Reversed:

Can someone please look at my code and see what is going on. I have tried quite a few things but cannot get anything to work.

#include <stdio.h>
#include <iostream>

#include "linkedStack.h"

using namespace std;

template <class Type>
void printStack(linkedStackType<Type>& stack);

template <class Type>
void reverseStack(linkedStackType<Type>& stack);

int main(int argc, char **argv)
{
   // Declare stack variables
   linkedStackType<int> stack;

   // Add some data to the stack
   stack.push(121);
   stack.push(113);
   stack.push(734);
   stack.push(22);
   stack.push(243);
   stack.push(34);
   stack.push(26);
   stack.push(74);
   stack.push(115);
   stack.push(262);

   cout << "\nStack:\n   ";
   printStack(stack);

   reverseStack(stack);

   cout << "\nStack Reversed:\n   ";
   printStack(stack);

   cout << "\n\n** Press any key to continue **\n";
   getchar();

   return 0;
}

template <class Type>
void printStack(linkedStackType<Type>& stack)
{
   Type item;
   linkedStackType<Type> tmpStack = stack;

   while (stack.isEmptyStack() == false)
   {
      item = stack.top();
      stack.pop();
      cout << item << " ";
   }

   stack = tmpStack;



 }

template <class Type>
void reverseStack(linkedStackType<Type>& stack)
{
  Type item;
   linkedStackType<Type> tmpStack;

   while (stack.isEmptyStack() == false)
   {
      item = stack.top();
      stack.pop();
      tmpStack.push(item);
   }

   while (tmpStack.isEmptyStack() == false)
   {
      item = tmpStack.top();
      tmpStack.pop();
      stack.push(item);
      cout << item;  

   }

   stack = tmpStack;


   return;
}

It will be very difficult to help you without being able to see the code behind `linkedStackType`. — Bill Lynch, Mar 26 '13 at 22:14
Not the solution, but the code copies the stack four times. It's easy to get this down to two copies. It can be done with only one copy. — Pete Becker, Mar 26 '13 at 22:17
@sharth: Actually, at least one bug is in the code shown, so that's less of an issue than it'd normally be. — Mooing Duck, Mar 26 '13 at 22:20

score 11 · Answer 1 · answered Mar 26 '13 at 22:16

I'm not 100%, but I imagine your code will work if you delete the second while loop of reverseStack.

template <class Type>
void reverseStack(linkedStackType<Type>& stack)
{
   Type item;
   linkedStackType<Type> tmpStack;

   while (stack.isEmptyStack() == false)
   {
      item = stack.top();
      stack.pop();
      tmpStack.push(item);
   }

   //while (tmpStack.isEmptyStack() == false)
   //{
   //   item = tmpStack.top();
   //   tmpStack.pop();
   //   stack.push(item);
   //   cout << item;
   //}

   stack = tmpStack;
   return;
}

Yep! This change produces the desired output. 100% – Drew Dormann Mar 26 '13 at 22:38 — Drew Dormann, Mar 26 '13 at 22:38

score 1 · Answer 2 · answered Mar 26 '13 at 22:18

1

You have an extraneous print loop in reverseStack() which prints the values in the wrong place. In addition this print loop clears your tmpStack. This explains the result.

answered Mar 26 '13 at 22:18

Johannes Overmann

4,914
22
38

score 1 · Answer 3 · answered Mar 26 '13 at 22:18

1

Your second while loop empties tmpStack, but then you assign the now-empty stack to stack, so you just have an empty stack.

answered Mar 26 '13 at 22:18

Kyle Strand

15,941
8
72
167

1

@SongWang: no, the stack is never doubled. It's simply printed twice before it's erased entirely. – Mooing Duck Mar 26 '13 at 22:25
Thanks for the explanation.. That makes sense. I am sitting here trying to figure out what to add and its as simple as taking away items. – Gavon Black Mar 26 '13 at 22:30
Thanks for pointing that out, Mooing Duck. Song Wang, yeah, that tripped me up at first too, but then I saw that `Stack Reversed` didn't have anything below it. – Kyle Strand Mar 26 '13 at 22:32

Luca Desogus · Answer 4 · 2022-06-22T10:40:54.373

This is my solution to reverse the std::stack content:

#include <stack>
#include <algorithm>    

template <class T>
class _stack : public std::stack<T>
{
    public:
        void reverse()
        {
            std::reverse(this->c.begin(),this->c.end());
        }
};
    
template <class T>
bool reverseStack(std::stack<T> & stack)
{
    bool ret = false;
    auto * s = reinterpret_cast<_stack<T>*> (&stack);
    if(s)
    {
        s->reverse();
        ret = true;
     }
     return ret;
}
    
int main()
{
   std::stack<int> stack;
   stack.push(1);
   stack.push(2);
   stack.push(3);
   stack.push(4);
   stack.push(5);
    
   reverseStack(stack);
}

You can use the same approach to access the cointeiner and print the values using iterators.

Ankur Lathiya · Answer 5 · 2015-10-11T07:04:41.997

-1

void sortStack(struct stack **s)  
{  
if (!isEmpty(*s))  
  {  
    int x = pop(s);  
    sortStack(s);  
    sortedInsert(s, x);  
  }  
}  

void sortedInsert(struct stack **s, int x)  
{  
  if (isEmpty(*s) || x > top(*s))  
  {  
    push(s, x);  
    return;  
  }  
int temp = pop(s);  
sortedInsert(s, x);  
push(s, temp);  
}

edited Oct 11 '15 at 07:04

answered Oct 11 '15 at 06:57

Ankur Lathiya

176
1
9

1

Some description about your code would be nice for later follow-up. – GHajba Oct 11 '15 at 07:14

how to reverse a stack

5 Answers5