My program is suppose to read in numbers and tokens. However, it will only read in the first number and go into a loop. Never reads the next number or does the computations. Can't figure out what's wrong.

#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
#include <cmath>
#include <vector>
#include <cstdlib>
#include <cstdio>
//____________________________________________________________________________________

using namespace std;

//____________________________________________________________________________________
#include "Stack03.h"
#include "Scan03.h"
//____________________________________________________________________________________


void PostfixMgr(FILE* i, ostream& o);
//____________________________________________________________________________________

int main(int argc, char* argv[]) 
{
	

	try
	{
	char infile[255];   // input file
	char outfile[255];  // output file

	
		if (argc == 1)
		{
			cout << " Enter the input file name. " << endl;
			cin >> infile;
			cout << " Enter the output file name. " << endl;
			cin >> outfile;
			cout << endl;
		}
		
		
	        else if (argc == 2)
		{
			strcpy(infile, argv[1]);
			cout << " Enter the output file name. " << endl;
			cin >> outfile;
			cout << endl;
			
		}
		else if ( argc == 3)
		{
			strcpy(infile, argv[1]);
			strcpy(outfile, argv[2]);
		}
		else
		{
			throw CommandLineException(2,argc -1);
		}		
	
	FILE* i= fopen(infile,"r");
		if(!i)
			throw FileException(infile);

	ofstream o(outfile);
		if(!o)
			throw FileException(outfile);

	

		
		PostfixMgr(i,o);


		fclose(i);

		} catch(...)
		{
		cout <<  " Program Terminated. " << endl;
		exit(EXIT_FAILURE);
		}


		return 0;
} // end of main.
void PostfixMgr(FILE* i, ostream& o)
{
	Scan L(i);
	Stack s;
	int k = 0;
	int front=0;
	int back = 0;
	int divisor =0;
	int div = 0;
	int answer = 0;
	int counter = 0;

			
			for(;;)
			{
				int t=L.Lex();
				if(t==0)
				{
					break;
				
				cout << endl;
				cout << setw(4) << t;
				cout << setw(30) << L.FetchSpelling();
				}
				switch (t)
				{
					case INTLIT:
						sscanf(L.FetchSpelling(),"%d",&k);
						s.Push(k);
					break;

					case PLUS:
						 s.Push(s.Pop() + s.Pop());

						
					break;

					case MINUS:
						back = s.Pop();
						front = s.Pop();
						s.Push(front - back);
						
					break;

					case SLASH:
						div = s.Pop();
						divisor = s.Pop();
						s.Push(divisor/div);
						
					break;
						
					case STAR:
						s.Push(s.Pop() + s.Pop());
						
					break;

					default:

						cout << " Did not recognize token" << endl;
						cout << endl;
					break;
				}	// end of switch statement.


				
				while ( !s.Is_Empty())
				{
					o << "S[tos]=" << " " << s.Pop() << endl;
					o << endl;
					counter++;
				}  // end of while loop. 




				
			} // end of for loop.
}  // end of PostfixMgr
#include <cstdio>
#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
#include <cmath>
#include <vector>
#include <cstdlib>
//____________________________________________________________________________________

using namespace std;
//____________________________________________________________________________________
#include "Stack03.h"


CommandLineException::CommandLineException(int max, int actual)
{	
		cout << " Too many command line arguments. " << endl;
}
//____________________________________________________________________________________
FileException::FileException(char* fn)
{
		cout << " File " << fn << " could not be opened. " << endl;
}



//____________________________________________________________________________________

Stack::Element::Element(Element* p, int v)
{
	prev = p;		// initialization of variables of class Element.
	value = v;		// initialization of variables of class Element.
}
//____________________________________________________________________________________
Stack::Element* Stack::Element::Prev(void)
{
	return prev;
}
//____________________________________________________________________________________
int Stack::Element::Value(void)
{
	return value;
}
//____________________________________________________________________________________
//____________________________________________________________________________________
Stack::StackException::StackException(char* m)
{
	cout << endl;
	cout << " I am the stack and I am " << m << " . " << endl;
}
//____________________________________________________________________________________
Stack::Stack()
{
	top_of_stack = 0;	// initialization of variables of class Stack.
}
//____________________________________________________________________________________
Stack::~Stack()
{
	Kill(top_of_stack);
}
//____________________________________________________________________________________
void Stack::Kill(Element* e)
{
	while(e)
	{
		Element* p = e;
		e = e->Prev();
		delete[]p;
	}		// end of while loop.
}
//____________________________________________________________________________________
bool Stack::Is_Full(void)
{
	return false;
}
//____________________________________________________________________________________
bool Stack::Is_Empty(void)
{
	return top_of_stack == 0;
}
//____________________________________________________________________________________
void Stack::Push(int v)
{
	if (Is_Full())
	{
		throw StackException("Full");
	}
	Element* n = new Element(top_of_stack,v);
	top_of_stack = n;
}
//____________________________________________________________________________________
int Stack::Pop(void)
{
	if (Is_Empty())
	{
		throw StackException("Empty");
	}
	Element* n = top_of_stack;
	int v=n->Value();
	top_of_stack = n;
	delete[]n;
	return v;
}
#ifndef STACK_H
#define STACK_H

#include <cstdio>
#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
#include <cmath>
#include <vector>
#include <cstdlib>
//____________________________________________________________________________________
using namespace std;

class CommandLineException
{	
		public:
	
			CommandLineException(int max, int actual);
	
};
//____________________________________________________________________________________	
class FileException
{
	public:
	
	FileException(char* fn);
};	
//____________________________________________________________________________________	

class Stack
{
	class Element
	{
		private:
			Element* prev;
			int value;
		
		public:
			Element(Element*p, int v);  // member function of class Element
			Element* Prev(void);		// member function of class Element
			int Value(void);			// member function of class Element
	};  // end of the class Element

	//____________________________________________________________________________________
class StackException
{
		public:
			StackException(char* m);  // constructor of class StackException
};  // end of class StackException

	


	private:
		Element* top_of_stack;
		void Kill(Element* e); // member function of class Stack
	
	public:

		Stack();
		~Stack();
		bool Is_Full(void);
		bool Is_Empty(void);
		void Push(int v);
		int Pop(void);

};	// end of class Stack

#endif
#include <string>                          
#include <cstdlib>
#include <iostream>
#include <fstream>
using namespace std;
//--------------------------------------------------------------------
// Application Includes                                               
//--------------------------------------------------------------------
#include "Scan03.h"
//--------------------------------------------------------------------
//Function prototypes
//--------------------------------------------------------------------
int TokenMgr(int T);
//--------------------------------------------------------------------
//Global Variables                                                    
//--------------------------------------------------------------------
%}
%%
[ \t\n]+                           ;
[+-]?[0-9]+                        {   
                                        return(TokenMgr(INTLIT));
                                   }
"+"                                {    
                                        return(TokenMgr(PLUS));
                                   }
"-"                                {    
                                        return(TokenMgr(MINUS));
                                   }
"*"                                {    
                                        return(TokenMgr(STAR));
                                   }
"/"                                {    
                                        return(TokenMgr(SLASH));
                                   }
%%
//--------------------------------------------------------------------
int TokenMgr(int T)
{  return T;
}
//--------------------------------------------------------------------
//Class Scan implementation
//--------------------------------------------------------------------
//Constructor Scan is used to redirect the input file stream from the
//keyboard to input file stream i.
//--------------------------------------------------------------------
Scan::Scan(FILE* i)
{  yyin=i;
}
//--------------------------------------------------------------------
//Function Lex calls yylex
//--------------------------------------------------------------------
int Scan::Lex(void)
{  return tokencode=yylex();
}
//--------------------------------------------------------------------
//Function FetchSpelling returns a pointer to the spelling of the most
//recent token.
//--------------------------------------------------------------------
char* Scan::FetchSpelling(void)
{  return (char*)yytext;
} 
//--------------------------------------------------------------------
//Function FetchTokenCode returns the code of the most recent token 
//--------------------------------------------------------------------
int Scan::FetchTokenCode(void)
{  return tokencode;
}
//--------------------------------------------------------------------
//Function StoreTokenCode records the most recent token code
//--------------------------------------------------------------------
void Scan::StoreTokenCode(int T)
{  tokencode=T;
}
//-----------------------End of Lex Definition--
#include <cstdio>
#include <fstream>
#include <iostream>
//--------------------------------------------------------------------
//Namespaces
//--------------------------------------------------------------------
using namespace std;
//--------------------------------------------------------------------
//Token code definitions
//--------------------------------------------------------------------
#define INTLIT 1
#define PLUS   2
#define MINUS  3
#define STAR   4
#define SLASH  5
//--------------------------------------------------------------------
                                                
//--------------------------------------------------------------------
#ifdef __cplusplus
extern "C" 
#endif
int yylex (void);
//--------------------------------------------------------------------
//Class Scan defines the attributes of a Scanner
//--------------------------------------------------------------------
class Scan {
  int tokencode;                 //Code for the most recent token found
public:
  Scan(FILE* i);                 //Redirect the input source from the 
                                 //keyboard to input file i.
  int Lex(void);                 //Call the scanner yylex and return the code
                                 //found by yylex
  int FetchTokenCode(void);      //Return the code of the most recent token
  void StoreTokenCode(int T);    //Store the token code.
  char* FetchSpelling(void);     //Return the spelling of the most recent
                                 //token
};
#endif
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