stack is not working

[mika23]

Hi so my stack program is supposed to allow a user to enter a postfix expression and provide the result or an underflow, overflow error message. Example the user enters 345*. I am very lost and do not know what to add or change to make this work. Please can someone help?

//header
const int MAX = 10;   
                       
typedef int tin_t;     


class stack
  { 

   private:

        tin_t     tin[MAX];       
        int      top;           

   public: 

 
        class Overflow{};
        class Underflow{};

      	stack();   // constructor
      	~stack();  // destructor  

     
        void push(tin_t);
        void pop(tin_t&);

      
        void topElem(tin_t&);
       bool isEmpty(); 
      	bool isFull();
        void displayAll(); 
        void clearIt(); 
        
  };  

//stack.cpp file
#include <iostream>
#include "stack.h"
using namespace std;

stack::stack()
{ top = -1; // indicate an empty stack }

stack::~stack()
  { // nothing to do }

bool stack::isEmpty()
{ if (top == -1) return true; else return false; )
  
bool stack::isFull()
  { if (top == MAX-1 ) return true; else return false; }
  

void stack::push(el_t elem)
  { if (isFull()) stackError(“overflow”);
    else { top++; tin[top] = elem; }}
  

void stack::pop(tin_t& elem)
  { if (isEmpty()) stackError(“stack underflow”);
    else { elem = tin[top]; top--;}}


void stack::topElem(tin_t& elem)
  { if (isEmpty()) stackError(“stack is empty”);
    else { elem = tin[top]; } }

void stack::displayAll()
  {  if (isEmpty()) cout << .[ empty ]. << endl;
    else for (int i=top; i>=0; i--)
      { cout << tin[i] << endl; }}

void stack::clearIt()
{  tin_t getrid;
   while( !isEmpty())
     pop(getrid);
}

//main.cpp
#include <iostream>
#include <string>
#include "stack.h"
using namespace std;

int main()
{
  stack postfixstack;  
  string expression;

  cout << "type a postfix expression: " ;
  cin >> expression;

  int i = 0;  
  char item;

  int box1;  
  int box2;  

  while (expression[i] != '\0')
    {
    try
       {
	
	 item = expression[i];
	
         if (isdigit(item)) {int x = int(expression[i]) - 48;;  postfixstack.push(item); }
	
         else if ( (item == '+') || (item == '-') || (item == '*'))
	   {
	     postfixstack.pop(box1);
	     postfixstack.pop(box2);
             // a whole bunch of cases
             if (item == '+') result = box1+box2;
             if (item == '-') result = box2-box1;
             if (item == '*') result = box2*box1;
             // push the result
	   }

    // Catch exceptions and report problems and quit the program now. 
    catch (stack::overflow)
      {cout<<"overflow"<<endl;  }
    catch (stack::underflow)
      {cout<<"Empty stack"<<endl; }
    catch (string errorcode)
      {cout<<"Error"<<endl; }
    }


    }

[kbw]

You should probably start with code that compiles. It's not clear whether you have issues with the syntax or the logic. In any event, you can only work with one at a time.