Stack Postfix Calculator

I read a post about the same thing and didn't know how to comment on it so I just made a new thread. Here's the code and couldn't get it to run. If anyone could look at this and tell me what's wrong with it that'd be great. I get an answer, but its wrong, for example 23+ gives me 225.

Code:

---

#include <iostream>
#include <iomanip>
using namespace std;
 
class node
{
  public:
    float number;
    node *next;
};
 
node* push(node *stack, float data)
{
  node *utility;
  utility = new node;
  utility -> number = data;
  utility -> next = stack;
  return utility;
}
 
node* pop(node *stack, float &data)
{
  node *temp;
  if (stack != NULL)
  {
    temp = stack;
    data = stack -> number;
    stack = stack -> next;
    delete temp;
  }
  else cout << "\nERROR: Empty stack.\n";
  return stack;
}
 
int main()
{
  float answer, operand1, operand2;
  char ch = ' ';                                   
  node *utility, *top;
 
  utility = new node;
  utility -> number = 0;
  utility -> next = NULL;
  top = new node;
  top -> number = 0;
  top -> next = utility;


  while(ch != 'q')
  {
 cout << "calc> ";
 cin >> noskipws >> ch;
    if(ch == 'q')
    {
        return 0;
    }
 while(ch != '\n')
 {
     
       
        float operand = 0;
        if((ch >= '0')&&(ch <= '9'))
        {
          while(ch != '\n')
          {
            operand = operand*10 + (ch-48);
             
            cin >> ch;
          }
          top = push(top, operand);
        }
        else
        {
            if((ch == '+')||(ch == '-')||(ch == '*')||(ch == '/')){
          top = pop(top, operand1);
          top = pop(top, operand2);
          switch(ch){
            case '+': answer = operand2 + operand1;
                break;
            case '-': answer = operand2 - operand1;
                break;
            case '*': answer = operand2 * operand1;
                break;
            case '/': answer = operand2 / operand1;
                break;
          }
          top = push(top, answer);}
            else {
                cout << "Error! Wrong Character Entered";
            }
        }
        pop(top, answer);
  cout << "\nAnswer: " << answer << endl;
 
}
  }
}

---

I can't find the error at first glance, but let me just ask you, why are you implementing your own stack for this? This has been done a million times before, don't reinvent the wheel, use std::stack, then you can focus on getting the RPN and arithmetics correct.

Also, why on earth would you use a linked-list for a stack implementation? What's wrong with an array, seems much simpler! (Or even better, a std::vector!)

I guess the answer is to add some DEBUG code to help you figure out where it's going wrong.
Though at some point, it's better to learn how to use a debugger.

Anyway.

Code:

---

#include <iostream>
#include <iomanip>
using namespace std;

class node {
public:
  float number;
  node *next;
};

node *push(node * stack, float data)
{
  node *utility;
  utility = new node;
  utility->number = data;
  utility->next = stack;
  return utility;
}

node *pop(node * stack, float &data)
{
  node *temp;
  if (stack != NULL) {
    temp = stack;
    data = stack->number;
    stack = stack->next;
    delete temp;
  } else
    cout << "\nERROR: Empty stack.\n";
  return stack;
}

int main()
{
  float answer, operand1, operand2;
  char ch = ' ';
  node *utility, *top;

  utility = new node;
  utility->number = 0;
  utility->next = NULL;
  top = new node;
  top->number = 0;
  top->next = utility;

  while (ch != 'q') {
    cout << "calc> ";
    cin >> noskipws >> ch;
    if (ch == 'q') {
      return 0;
    }
    while (ch != '\n') {
      float operand = 0;
      if ((ch >= '0') && (ch <= '9')) {
        while (ch != '\n') {
          operand = operand * 10 + (ch - 48);
          cin >> ch;
        }
        cout << "Debug: pushed " << operand << endl;
        top = push(top, operand);
      } else {
        if ((ch == '+') || (ch == '-') || (ch == '*') || (ch == '/')) {
          top = pop(top, operand1);
          top = pop(top, operand2);
          cout << "Debug: popped " << operand1 << " " << operand2 << endl;
          switch (ch) {
          case '+':
            answer = operand2 + operand1;
            break;
          case '-':
            answer = operand2 - operand1;
            break;
          case '*':
            answer = operand2 * operand1;
            break;
          case '/':
            answer = operand2 / operand1;
            break;
          }
          top = push(top, answer);
        } else {
          cout << "Error! Wrong Character Entered";
        }
      }
      pop(top, answer);
      cout << "\nAnswer: " << answer << endl;
    }
  }
}

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